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 Talk Talk - Communication terms
Category: General technical and industrial
Date & country: 28/05/2010, UK
Words: 18630


Haiti
Country in the Caribbean, occupying the western part of the island of Hispaniola; to the east is the Dominican Republic. Government Haiti has a multiparty political system, with a presidential and prime ministerial dual political executive, on the French model. Its 1987 constitution provides for two-chamber legislature, the National Assembl...

Harvard University
The oldest educational institution in the USA, founded in 1636 at New Towne (later Cambridge), Massachusetts, and named after John Harvard (1607–1638), who bequeathed half his estate and his library to it. Women were first admitted in 1969; the women's college of the university is Radcli...

Hawke, Bob
(Robert James Lee) Australian Labor politician, prime minister 1983–91, on the right wing of the party. He was president of the Australian Council of Trade Unions 1970–80. He announced his retirement from politics in 1992. He retired after his former finance minister, Paul Keating, d...

Haakon IV
King of Norway from 1217, the son of Haakon III. Under his rule, Norway flourished both militarily and culturally; he took control of the Faroe Islands, Greenland in 1261, and Iceland 1262–64. His court was famed throughout northern Europe

haggis
Scottish dish made from a sheep's or calf's heart, liver, and lungs, minced with onion, oatmeal, suet, spices, and salt, mixed with stock, and traditionally boiled in the animal's stomach for several hours

ha
Symbol for hectare

Harry
(prince of the UK) Prince of the UK; second child of Charles, Prince of Wales, and his first wife, Diana, Princess of Wales. Harry attended Ludgrove School, Wokingham (1992–97) Eton College, Windsor (1998–2003), and Sandhurst 2005–06. As a troop commander in the British Army...

hay
Preserved grass used for winter livestock feed. The grass is cut and allowed to dry in the field before being removed for storage in a barn. The optimum period for cutting is when the grass has just come into flower and contains most feed value. During the natural drying process, the moisture content...

haematology
Medical speciality concerned with disorders of the blood

haemostasis
Natural or surgical stoppage of bleeding. In the natural mechanism, the damaged vessel contracts, restricting the flow, and blood platelets plug the opening, releasing chemicals essential to clotting

Hadith
Collection of the teachings of Muhammad and stories about his life, regarded by Muslims as a guide to living second only to the Koran. The teachings were at first transmitted orally, but this led to a large number of Hadiths whose origin was in doubt; later, scholars such as Muhammad al-Bukhari (810–870) collected together those believ...

hajj
Pilgrimage to Mecca (Arabic Makkah), in Saudi Arabia, that should be undertaken by every Muslim at least once in a lifetime, unless he or she is prevented by financial or health difficulties. A Muslim who has been on hajj may take the additional name Hajji. Many of the pilgrims on hajj also visit Medina, where the prophet Muhammad is buried

halal
Conforming to the rules laid down by Islam. The term can be applied to all aspects of life, but usually refers to food permissible under Muslim dietary laws, including meat from animals that have been slaughtered in the correct ritual fashion. Unlawful practices are known as haram

Hanukkah
In Judaism, an eight-day festival of dedication and lights that takes place at the beginning of December. It celebrates the recapture of the Temple in Jerusalem from Antiochus IV of Syria in 164 BC by Judas Maccabaeus, and its rededication. During Hanukkah, candles are lit each night and placed in a nine-branched candlestick, or hanukkiah&#...

Hargobind
Indian religious leader, sixth guru (teacher) of Sikhism 1606–44. He encouraged Sikhs to develop military skills in response to growing persecution, and became both a spiritual leader and the head of an organized and successful Sikh army. At the festival of Diwali, Sikhs celebrate his release from prison. Arjan, Hargobind's father and pred...

Har Krishen
Indian religious leader, eighth guru (teacher) of Sikhism 1661–64, who died at the age of eight

Har Rai
Indian religious leader, seventh guru (teacher) of Sikhism 1644–61. The grandson of his predecessor Hargobind, Har Rai was ordained guru at the age of 14. He protected the Adi Granth, the holy book that was to become the Guru Granth Sahib, from any change, against the wishes of the Mogul emperor Aurangzeb,...

Hamilton, Richard
English artist, a pioneer of pop art. His collage Just What Is It That Makes Today's Homes So Different, So Appealing? (1956; Kunsthalle, Tübingen, Germany) is often cited as the first pop-art work: its 1950s interior, inhabited by the bodybuilder Charles Atlas and a pin-up, is typically humorous, concern...

Hastings, Battle of
Battle on 14 October 1066 at which William, Duke of Normandy (William (I) the Conqueror) defeated King Harold II of England. Harold was killed leaving the throne open for William to complete the Norman Conquest. The site is 10 km/6 mi inland from Hastings, at Senlac, Sussex; it is marked by Battle Abbey. The story of the battle is told in a...

hacking
Unauthorized access to computer systems, either for fun or for malicious or fraudulent purposes. Hackers generally use computers and telephone lines to obtain access. In computing, the term is used in a wider sense to mean using software for enjoyment or self-education, not necessarily involving unauthorized access. The most destructive form of...

Hasidism
Sect of Orthodox Judaism, originating in 18th-century Poland under the leadership of Israel Ba'al Shem Tov (c. 1700–1760), also known as Besht. Hasidic teachings encourage prayer, piety, and `serving the Lord with joy`. Many of the Hasidic ideas are based on the Kabbalah, a mystical Jewish tradition. Hasidi...

Harbin
Port and capital of Heilongjiang province, northeast China, on the Songhua River; population (2000) 3,627,100. It is a major rail junction. Industries include metallurgy, food-processing, and sugar-refining; the manufacture of machinery, ball bearings, chemicals, cement, and paper; and tourism. Harbin was developed by Russian se...

Hardouin-Mansart, Jules
French architect born in Paris. He superintended the construction of all the principal buildings of Louis XIV, including the lavish baroque extensions to the palace of Versailles (1678–1708), its colonnade, the cathedral, and the Grand Trianon. His other works in Paris include the dome of the H&...

Hatshepsut
Queen (pharaoh) of ancient Egypt during the 18th dynasty. She was the daughter of Thutmose I, and the wife and half-sister of Thutmose II. Throughout his reign real power lay with Hatshepsut, and she continued to rule after his death, as regent for her nephew Thutmose III. Her reign was a peacefu...

Hasdrubal Barca
Carthaginian general, son of Hamilcar Barca and younger brother of Hannibal. He remained in command in Spain when Hannibal invaded Italy during the Second Punic War and, after fighting there against Scipio until 208, marched to Hannibal's relief. He was defeated and killed in the Metaurus valley, northeastern Italy

Haute-Normandie
Coastal region of northwest France lying between Basse-Normandie and Picardy and bisected by the River Seine; area 12,317 sq km/4,756 sq mi; population (1999 est) 1,780,200. It comprises the départements of Eure and Seine-Maritime; its administrative centre is Rouen. Other chief towns include Évr...

Hampton Court Palace
Former royal residence near Richmond, England, 24 km/15 mi west of central London. Hampton Court is one of the greatest historical monuments in the UK, and contains some of the finest examples of Tudor architecture and of Christopher Wren's work. It was built in 1515 by Cardinal Wolsey and pr...

Hackman, Gene
US actor. He won an Academy Award for Best Actor for his performance as `Popeye` Doyle in The French Connection (1971), and has continued to play mainly combative roles in such films as Night Moves (1975), Mississippi Burning (1988), Unforgiven (1992; Academy ...

Hayworth, Rita
US dancer and film actor. She gave vivacious performances in 1940s musicals and played erotic roles in Gilda (1946) and Affair in Trinidad (1952). She was married to Orson Welles 1943–48 and appeared in his film The Lady from Shanghai (1948). She gave assured performances in Pal...

Hays Office
Film regulation body in the USA 1922–45. Officially known as the Motion Picture Producers and Distributors of America, it was created by the major film companies to improve the industry's image and provide internal regulation, including a strict moral code. The office was headed by Will H Hays (1879–1954). A Production Code, listing a...

hard disk
In computing, a storage device usually consisting of a rigid metal disk coated with a magnetic material. Data are read from and written to the disk by means of a disk drive. The hard disk may be permanently fixed into the drive or in the form of a disk pack that can be removed and exchanged with a different pack. Hard disks can have capacities as h...

halon
Organic chemical compound containing one or two carbon atoms, together with bromine and other halogens. The most commonly used are halon 1211 (bromochlorodifluoromethane) and halon 1301 (bromotrifluoromethane). The halons are gases and were once widely used in fire extinguishers. As destroyers of the ozone layer, they are up to ten times more effec...

half-life
During radioactive decay, the time in which the activity of a radioactive source decays to half its original value (the time taken for half the atoms to decay). In theory, the decay process is never complete and there is always some residual radioactivity. For this reason, the half-life of a radioactive isotope is measured, rather than the tota...

halide
Any compound produced by the combination of a halogen, such as chlorine or iodine, with a less electronegative element (see electronegativity). Halides may be formed by ionic bonds (such as common table salt, sodium chloride) or by covalent bonds (such as alkyl halides, organic molecules consisting of a halogen and an alkyl group, such as methyl ch...

hard water
Water that does not lather easily with soap, and produces a deposit or scale (limescale) in kettles. It is caused by the presence of certain salts of calcium and magnesium. Temporary hardness is caused by the presence of dissolved hydrogencarbonates (bicarbonates); when the water is boiled, they are converted to insoluble carbonates that precip...

Hammond organ
Electric organ invented in the USA by Laurens Hammond in 1934. It is widely used in gospel music. Hammond applied valve technology to miniaturize Thaddeus Cahill's original `tone-wheel` concept, introduced draw-slide registration to vary timbre, and added a distinctive tremulant using rotating speakers. The synthesizer was dev...

hang-gliding
Technique of unpowered flying using air currents, perfected by US engineer Francis Rogallo in the 1970s. The aeronaut is strapped into a carrier, attached to a sail wing of nylon stretched on an aluminium frame like a paper dart, and jumps into the air from a high place, where updraughts of warm air allow soaring on the thermals. See gliding

Harlem Globetrotters
US touring basketball team that plays exhibition matches worldwide. Comedy routines as well as their great skills are features of the games. They were founded in 1927 by Abraham Saperstein (1903–1966)

halite
Mineral form of sodium chloride, NaCl. Common salt is the mineral halite. When pure it is colourless and transparent, but it is often pink, red, or yellow. It is soft and has a low density. Halite occurs naturally in evaporite deposits that have precipitated on evaporation of bodies of salt water. As rock salt, it forms beds within a sedimentary se...

Harlow, Jean
US film actor. She was the original `platinum blonde` and the wisecracking sex symbol of the 1930s. Her films include Hell's Angels (1930), Red Dust (1932), Platinum Blonde (1932), Dinner at Eight (1933), China Seas (1935), and Sara...

Hammerstein, Oscar, II
US lyricist and librettist. He collaborated with Richard Rodgers over a period of 16 years on some of the best-known US musicals, including Oklahoma! (1943, Pulitzer Prize), Carousel (1945), South Pacific (1949, Pulitzer Prize), The King and I (1951), and T...

Hall, Radclyffe
English novelist. The Well of Loneliness (1928) brought her notoriety because of its lesbian theme. It was successfully prosecuted for obscenity and banned in the UK, but republished in 1949. Her other works include the novel Adam's Breed (1926; Femina Vie Heureuse and Tait Black Memorial prizes) and fi...

hadron
In physics, a subatomic particle that experiences the strong nuclear force. Each is made up of two or three indivisible particles called quarks. The hadrons are grouped into the baryons (protons, neutrons, and hyperons), consisting of three quarks, and the mesons, consisting of two quarks

Harrison, Tony
English poet, translator, and dramatist. He caused controversy with his poem `V` (1987), dealing with the desecration of his parents' grave by Liverpool football supporters, and the play The Blasphemers' Banquet (1989), which attacked (in the name of the writers Molière, Voltaire, Byron, and Omar Khayyam) t...

hawk
(politics) Person who believes in the use of military action rather than mediation as a means of solving a political dispute. The term first entered the political language of the USA during the 1960s, when it was applied metaphorically to those advocating continuation and escalation of the Vie...

hardcore
In pop music, of any style, the more extreme and generally less commercial end of the spectrum: hardcore techno is a minimalist electronic dance music; hardcore rap is aggressive or offensive; hardcore punk jettisons form and melody for speed and noise. There are several main tendencies within hardcore punk. The very similar styles know...

Hammer, Armand
US entrepreneur, one of the most remarkable business figures of the 20th century. A pioneer in trading with the USSR from 1921, he later acted as a political mediator. He was chair of the US oil company Occidental Petroleum until his death, and was also an expert on art

Han
The majority ethnic group in China, numbering about 990 million. The Hans speak a wide variety of dialects of the same monosyllabic language, a member of the Sino-Tibetan family. Their religion combines Buddhism, Taoism, Confucianism, and ancestor worship

Harrison, Rex
(Reginald Carey) English film and theatre actor. He appeared in over 40 films and numerous plays, often portraying sophisticated and somewhat eccentric characters, such as the waspish Professor Higgins in My Fair Lady (1964; Academy Award), the musical version of
harness racing
Form of horse racing, also known as trotting or pacing, in which the horses are harnessed, pull a light vehicle (sulky) and compete at either a trotting or pacing gait. If a horse breaks the pace and gallops, the driver must start it again

hand
(measurement) Unit used in measuring the height of a horse from front hoof to shoulder (withers). One hand equals 10.2 cm/4 in

Hampton, Lionel
US jazz musician. He was a top bandleader of the 1940s and 1950s. Originally a drummer, Hampton introduced the vibraphone, an electronically vibrated percussion instrument, to jazz music. With the Benny Goodman band from 1936, he fronted his own big band 1941–65 and subsequently led small groups

Hagia Sophia
Click images to enlargeByzantine building in Istanbul, Turkey, built 532–37 as a Christian cathedral, replacing earlier churches. From 1453 to 1934 it was an Islamic mosque; in 1922 it became a museum. Byzantine mosaics have been uncovered on the upper gallery while the main floor has displays of Islamic mosque f...

hard copy
Computer output printed on paper

Haber-Bosch process
Industrial process in which ammonia is manufactured by direct combination of its elements, nitrogen and hydrogen. The reaction is carried out at 752–932°F/400–500°C and at a pressure of 200 bar. The two gases, in the proportions of 1:3 by volume, are passed over a catalyst of finely divided iron. Around 10% of the re...

hanging valley
Minor (tributary) valley that joins a larger glacial trough at a higher level than the trough floor. During glaciation the ice in the smaller valley was unable to erode as deeply as the ice in the trough, and so the valley was left perched high on the side of the trough when the ice retreated. A river or stream flowing along the hanging valley ofte...

hacienda
Large estate typical of most of Spanish colonial and post-colonial Latin America. Typically inherited, haciendas were often built up by the purchase of crown or private lands, or lands traditionally worked by the Indian community. They used cheap, seasonal labour to farm produce, fairly inefficiently, for domestic and export markets. Socially, ...

Han dynasty
Chinese ruling family from 206 BC to AD 220 established by Liu Bang (256–195 BC) after he overthrew the Qin dynasty, and named after the Han River. There was territorial expansion to the west, southwest, and north, including the conquest of Korea by Emperor Wudi or Wu-ti (ruling 141–87 BC) and the suppression of the Xiongnu invaders. ...

Hanging Gardens of Babylon
In antiquity, gardens at Babylon, the capital of Mesopotamia, considered one of the Seven Wonders of the World. According to legend, King Nebuchadnezzar constructed the gardens in the 6th century BC for one of his wives, who was homesick for her birthplace in the Iranian mountains. Archaeological excavations at the site of Babylon, 88 km/55 mi ...

harmonic minor scale
In music, one of the minor scales where the seventh note of the scale is raised (sharpened) by a semitone. It is so called because its notes are used when creating chords or harmonies

Hamed, `Prince` Naseem
English boxer, known as `Prince` Naseem for his showmanship in the ring. An exceptionally strong puncher for a featherweight, he is widely regarded as one of boxing's greatest talents. He made his professional debut in 1992 and was unbeaten until April 2001, when he lost on a unanimous points decision to Mexico's Marco Antonio Bar...

Hardenberg, Friedrich von
Real name of German Romantic poet Novalis

hatching
In drawing, the creation of areas of tone or shadow with a series of parallel lines. In cross-hatching the lines are then crossed by other parallel lines. It is often used to block in an area quickly and effectively. It is also found in the form of brushwork used in tempera painting and fresco to convey a depth or gradation of tone otherwise di...

hassium
Synthesized, radioactive element of the transactinide series, atomic number 108, relative atomic mass 265. First synthesized in 1984 by the Laboratory for Heavy-Ion Research in Darmstadt, Germany, it was known by the temporary name unniloctium until 1997

Hammond, Wally
English cricketer. One of the game's greatest players, he led the English first-class averages for eight consecutive seasons, 1933–39, and 1946. He was also a good medium-fast bowler and a brilliant slip fielder. Career highlights Test cricket (1927–47) appearances: 85; batting: runs: 7,249; average: 58...

Hale-Bopp
Large and exceptionally active comet, which in March 1997 made its closest fly-by to Earth since 2000 BC, coming within 190 million km/118 million mi. It has a nucleus of approximately 40 km/25 mi and an extensive gas coma (when close to the Sun Hale-Bopp released 10 tonnes of gas every second). Unusually, Hale-Bopp has three ta...

harlequinade
Entertainment popular in Britain in the 18th and 19th centuries, in which the principal characters were derived from the Italian commedia dell'arte. The story followed a set pattern, with the frantic pursuit of the eloping lovers Harlequin and Columbine by the father or guardian Pantaloon and his servant Pierrot. The genre was a combination of ...

Hartlepool
(town) Port and administrative centre of Hartlepool unitary authority in northeast England; 40 km/25 mi south of Newcastle upon Tyne; population (2001) 86,100. Historically a shipbuilding centre, modern industries include chemicals, metalwork, engineering, oil support services, fis...

Halton
Unitary authority in northwest England, created in 1998 from part of Cheshire. Area 74 sq km/29 sq mi Towns and cities Runcorn, Widnes (administrative headquarters), Ditton Features River Mersey divides Runcorn from Widnes and Ditton; Manchester Ship Canal and Bridgewater Canal reach Mersey at Runcorn; St Helen's Canal reaches Merse...

Hannibal
(person) Carthaginian general from 221 BC, son of Hamilcar Barca. His siege of Saguntum (now Sagunto, near Valencia) precipitated the Second Punic War with Rome. Following a campaign in Italy (after crossing the Alps in 218), Hannibal was the victor at Trasimene in 217 and Cannae in 216, but h...

Haley, Bill
US musician. A pioneering rock and roll singer, he led country-and-western bands around Philadelphia, Pennsylvania, between 1942 and 1952, when he formed the rhythm and blues-styled Bill Haley and His Comets. In 1954 his recordings of `Rock Around the Clock` and `Shake, Rattle and Roll` were among the earliest rock a...

Hakkinen, Mika Pauli
Finnish racing driver who won the 1998 and 1999 Formula 1 World Drivers' Championships. He made his Formula 1 debut in 1991 (for the Lotus-Judd team), a year after winning the British Formula 3 title. Switching to the McLaren team in 1993, he finished fourth in the championship in 1993 and 1994, and fifth in 1996, but it was not until the f...

half-rhyme
In verse, a rhyme in which the consonant sounds are similar but not the vowel sounds. For example, in her poem The Soul Selects, the US poet Emily Dickinson (a poet who made extensive use of half-rhyme) rhymes gate and mat, one and stone. In a more em...

Hadar
Second-brightest star in the constellation of Centaurus, and the 11th-brightest in the night sky. It is a blue-white giant star of magnitude 0.61, some 320 light years from the Sun. It is a binary star, comprising two stars of magnitudes 0.7 and 3.9

havan
Hindu sacred-fire ceremony conducted by a priest in a person's house or in a temple. Havans are held at weddings and many other ceremonial occasions. After lighting a fire, ghee (clarified butter) is poured on the flames, and prayers from the Vedas are recited. Incense and rice may be sprinkled into the fire as well, and prayers are said to...

haram
Forbidden under the laws of Islam. The term may be applied to transgressions in all aspects of life, from unlawful foodstuffs, such as meat from an animal that has not been killed in the prescribed way, to drinking intoxicating liquor and adultery. The distinction between what is halal (lawful) and what is haram is made by Allah, both through the K...

Hail Mary
Christian prayer to the Virgin Mary, most frequently used by Roman Catholics. It takes its name from the archangel Gabriel's salutation to Mary when announcing that she would be the mother of the Messiah (Luke 11:28). In Roman Catholic and some Anglican churches, the reciting of the rosary includes 150 Hail Marys

Hara Matsuri
Japanese Mahayana Buddhist festival, celebrating the birth of the Buddha. It is held in April, and commemorated by the planting of a grove of flowers. Images of the Buddha as a child are bathed in scented water or tea, and offerings are made at temples and shrines

Halachah
In Judaism, the oral legal tradition embodied in the Talmud (a compilation of Jewish law and tradition). Based on the Torah, it comprises rules, discussion, and commentary passed down by word of mouth. The Halachah regulates all aspects of conduct by describing the proper path through life. It is strictly observed by Orthodox Jews

Havdallah
In Jewish worship, a service of separation held both in the synagogue and at home to mark the end of Sabbath and holy festivals, such as Pesach. Havdallah is held after sunset, when the celebrations have ended. It marks the division of holy from secular, light from dark, Israel from other nations, and a holy day from the ordinary days of the year. ...

hafiz
In Islam, a title for those who have memorized the whole of the Koran (or Qur'an). There are thousands of Muslims worldwide who have achieved this spiritual quest. The significance of such an achievement is heightened when it is realized that for many who are granted the title hafiz, Arabic, the language of the Koran, is not their first languag...

Harimandir
Most sacred pilgrimage site in the Sikh religion. The two-storey temple located at Amritsar, in the Punjab region of India, shines with a roof of gilded cooper, and there are layers of gold decorating the inside. The four doors to the temple signify the welcome of the Sikhs to people regardless of their background. Pilgrims, but not tourists, w...

Harper, Stephen Joseph
Canadian right-of-centre politician, prime minister from 2006. Leader of the Conservative Party of Canada, he formed a minority government after the January 2006 federal elections, ending 12 years of Liberal government. His government was elected on a platform of reducing taxes and a stronger approach to law and order, with tougher sentence...

HDTV
Abbreviation for high-definition television

henbane
Poisonous plant belonging to the nightshade family, found on waste ground throughout most of Europe and western Asia. It is a branching plant, up to 80 cm/31 in high, with hairy leaves and a sickening smell. The yellow flowers are bell-shaped. Henbane is used in medicine as a source of the drugs hyoscyamine and scopolamine. (Hyoscy...

hemlock
Plant belonging to the carrot family, native to Europe, western Asia, and North Africa. It grows up to 2 m/6 ft high and produces delicate clusters of small white flowers. The whole plant, especially the root and fruit, is poisonous, causing paralysis of the nervous system. The name `hemlock` is also given to some North American and A...

heliotrope
Decorative plant belonging to the borage family, with distinctive spikes of blue, lilac, or white flowers, including the Peruvian or cherry pie heliotrope (H. peruvianum). (Genus Heliotropium, family Boraginaceae.)

hellebore
Poisonous European herbaceous plant belonging to the buttercup family. The stinking hellebore (H. foetidus) has greenish flowers early in the spring. (Genus Helleborus, family Ranunculaceae.)

heather
Low-growing evergreen shrub of the heath family, common on sandy or acid soil. The common heather (Calluna vulgaris) is a carpet-forming shrub, growing up to 60 cm/24 in high and bearing pale pink-purple flowers. It is found over much of Europe and has been introduc...

heath
In botany, any of a group of woody, mostly evergreen shrubs, including heather, many of which have bell-shaped pendant flowers. They are native to Europe, Africa, and North America. (Common Old World genera Erica and Calluna, family Ericaceae.)

Heath, Edward
(Richard George) British Conservative politician, party leader 1965–75. As prime minister 1970–74 he took the UK into the European Community (EC) but was brought down by economic and industrial-relations crises at home. He was replaced as party leader by Margaret Thatcher in 1975...

Hertzsprung-Russell diagram
In astronomy, graph on which the surface temperatures of stars are plotted against their luminosities. Most stars, including the Sun, fall into a narrow band called the main sequence. When a star grows old it moves from the main sequence to the upper right part of the graph, into the area of the gian...

Hercules
(astronomy) Fifth-largest constellation, lying in the northern hemisphere. Despite its size it contains no prominent stars. Its most important feature is the best example in the northern hemisphere of a globular cluster of stars 22,500 light years from the Sun, which lies between Eta and Z...

Henry, Joseph
US physicist, inventor of the electromagnetic motor in 1829 and of a telegraphic apparatus. He also discovered the principle of electromagnetic induction, roughly at the same time as Michael Faraday, and the phenomenon of self-induction. The unit of inductance, the henry, is named after him

heavy water
Water containing the isotope deuterium instead of hydrogen (relative molecular mass 20 as opposed to 18 for ordinary water). Its chemical properties are identical with those of ordinary water, but its physical properties differ slightly. It occurs in ordinary water in the ratio of about one part by mass of deuterium to 5,000 parts by mass of hydrog...

Heraclius
Byzantine emperor from 610. His reign marked a turning point in the empire's fortunes. Of Armenian descent, he recaptured Armenia in 622, and other provinces 622–28 from the Persians, but lost them to the Muslims 629–41

herring
Any of various marine fishes belonging to the herring family, but especially the important food fish Clupea harengus. A silvered greenish blue, it swims close to the surface, and may be 25–40 cm/10–16 in long. Herring travel in schools several kilometres long and wide. They are found in large quantities off the east...

heron
Large to medium-sized wading bird belonging to the same family as bitterns, egrets, night herons, and boatbills. Herons have sharp bills, broad wings, long legs, slender bodies, and soft plumage. They are found mostly in tropical and subtropical regions, but also in temperate zones, on lakes, fen...

hedgehog
Insectivorous mammal native to Europe, Asia, and Africa. The body, including the tail, is 30 cm/1 ft long. It is greyish brown in colour, has a piglike snout, and its back and sides are covered with sharp spines. When threatened it rolls itself into a ball bristling with spines. Hedgehogs feed on...

hedge sparrow
Another name for the dunnock, a small European bird