Pentane noun [ See Penta- .] (Chemistry) Any one of the three metameric hydrocarbons, C ₅ H ₁₂ , of the methane or paraffin series. They are colorless, volatile liquids, two of which occur in petroleum. So called because of the five carbon atoms in the molecule.

Pentangle noun [ Pent a- + angle .] A pentagon. [ R.] Sir T. Browne.

Pentangular adjective [ Pent a- + angular .] Having five corners or angles. [ R.]

Pentapetalous adjective [ Penta- + petal .] (Botany) Having five petals, or flower leaves.

Pentaphyllous adjective [ Penta- + Greek ... leaf.] (Botany) Having five leaves or leaflets.

Pentapody noun [ Penta- + Greek ..., ..., foot.] (Pros.) A measure or series consisting of five feet.

Pentaptote noun [ Latin ( pl .) pentaptota . Greek ... with five cases; ... (see Penta- ) + ... falling.] (Gram.) A noun having five cases.

Pentaptych noun [ Penta- + Greek ..., ..., a fold.] (Fine Arts) A picture, or combination of pictures, consisting of a centerpiece and double folding doors or wings, as for an altarpiece.

Pentarchy noun [ Greek ...: confer French pentarchie . See Penta- , and -archy .] A government in the hands of five persons; five joint rulers. P. Fletcher. "The pentarchy of the senses." A. Brewer.

Pentaspast noun [ Latin pentaspaston , Greek ... (see Penta- ) + ... to pull: confer French pentaspaste .] A purchase with five pulleys. [ R.]

Pentaspermous adjective [ Penta- + Greek ... seed.] (Botany) Containing five seeds.

Pentastich noun [ Greek ... of five verses; ... (see Penta- ) + ... line, verse.] A composition consisting of five verses.

Pentastichous adjective [ Penta- + Greek ... a row.] (Botany) Having, or arranged in, five vertical ranks, as the leaves of an apple tree or a cherry tree.

Pentastomida noun plural [ New Latin , from ... (see Penta- ) + ... a mouth.] (Zoology) Same as Linguatulina .

Pentastyle adjective [ Penta- + Greek ... a pillar.] (Architecture) Having five columns in front; - - said of a temple or portico in classical architecture. -- noun A portico having five columns.

Pentateuch noun [ Latin pentateuchus , Greek ...; ... (see Penta- ) + ... a tool, implement, a book, akin to ... to prepare, make ready, and perhaps to English text . See Five , and Text .] The first five books of the Old Testament, collectively; -- called also the Law of Moses , Book of the Law of Moses , etc.

Pentateuchal adjective Of or pertaining to the Pentateuch.

Pentathionic adjective [ Penta- + thionic .] (Chemistry) Pertaining to, or designating, an acid of sulphur obtained by leading hydrogen sulphide into a solution of sulphur dioxide; -- so called because it contains five atoms of sulphur.

Pentathlon noun [ New Latin , from Greek ...; ... five + ... a contest.] (Gr. Antiq.) A fivefold athletic performance peculiar to the great national games of the Greeks, including leaping, foot racing, wrestling, throwing the discus, and throwing the spear.

Pentathlon noun In the modern Olympic Games, a composite contest made up of a running broad jump, throwing the javelin, a 200-meter run, throwing the discus, and a 1500-meter run.

Pentatomic adjective [ Penta- + atomic .] (Chemistry) (a) Having five atoms in the molecule. (b) Having five hydrogen atoms capable of substitution.

Pentavalent adjective [ Penta- + Latin valens , present participle See Valence .] (Chemistry) Having a valence of five; -- said of certain atoms and radicals.

Penteconter noun [ Greek ... (sc. ...), from ... fifty.] (Gr. Antiq.) A Grecian vessel with fifty oars. [ Written also pentaconter .]

Pentecost noun [ Latin pentecoste , Greek ... (sc. ...) the fiftieth day, Pentecost, from ... fiftieth, from ... fifty, from ... five. See Five , and confer Pingster .]
1. A solemn festival of the Jews; -- so called because celebrated on the fiftieth day (seven weeks) after the second day of the Passover (which fell on the sixteenth of the Jewish month Nisan); -- hence called, also, the Feast of Weeks . At this festival an offering of the first fruits of the harvest was made. By the Jews it was generally regarded as commemorative of the gift of the law on the fiftieth day after the departure from Egypt.

2. A festival of the Roman Catholic and other churches in commemoration of the descent of the Holy Spirit on the apostles; which occurred on the day of Pentecost; -- called also Whitsunday . Shak.

Pentecostal adjective Of or pertaining to Pentecost or to Whitsuntide.

Pentecostals noun plural Offerings formerly made to the parish priest, or to the mother church, at Pentecost. Shipley.

Pentecoster noun [ New Latin , from Greek ..., from ... fifty.] (Gr. Antiq.) An officer in the Spartan army commanding fifty men. Mitford.

Pentecosty noun ; plural Pentecosties . [ Greek ..., from ... the fiftieth, ... fifty.] (Gr. Antiq.) A troop of fifty soldiers in the Spartan army; -- called also pentecostys . Jowett (Thucyd. ).

Pentelic, Pentelican adjective Of or pertaining to Mount Pentelicus, near Athens, famous for its fine white marble quarries; obtained from Mount Pentelicus; as, the Pentelic marble of which the Parthenon is built.

Pentene noun [ See Penta- .] (Chemistry) Same as Amylene .

Penthouse noun [ A corruption of pentice .] A shed or roof sloping from the main wall or building, as over a door or window; a lean-to. Also figuratively. "The penthouse of his eyes." Sir W. Scott.

Penthouse adjective Leaning; overhanging. " Penthouse lid." Shak. "My penthouse eyebrows." Dryden.

Pentice noun [ French appentis a penthouse. See Append .] A penthouse. [ Obsolete] Sir H. Wotton.

Pentile noun See Pantile .

Pentine noun [ See Penta- .] (Chemistry) An unsaturated hydrocarbon, C ₅ H ₈ , of the acetylene series. Same as Valerylene .

Pentoic adjective [ See Penta- .] (Chemistry) Pertaining to, or desingating, an acid (called also valeric acid ) derived from pentane.

Pentone noun [ See Penta- .] (Chemistry) Same as Valylene .

Pentosan noun Also -sane [ From Pentose .] (Chemistry) One of a class of substances (complex carbohydrates widely distributed in plants, as in fruits, gums, woods, hay, etc.) which yield pentoses on hydrolysis.

Pentose noun [ Penta- + - ose .] (Chemistry) Any of a group of sugars of the formula C ₅ H ₁₀ O ₅ , as arabinose; -- so called from the five carbon atoms in the molecule. They are not fermented by yeast.

Pentoxide noun [ Penta- + oxide .] (Chemistry) An oxide containing five atoms of oxygen in each molecule; as, phosphorus pentoxide , P ₂ O ₅ .

Pentremite noun (Zoology) Any species of Pentremites.

Pentremites noun [ New Latin , from Greek ... five + Latin remus an oar.] (Zoology) A genus of crinoids belonging to the Blastoidea. They have five petal-like ambulacra.

Pentroof noun [ French pente slope + English roof , or from pent house roof .] See Lean-to .

Pentrough noun A penstock.

Pentyl noun [ Pent a + - yl .] (Chemistry) The hypothetical radical, C ₅ H ₁₁ , of pentane and certain of its derivatives. Same as Amyl .

Pentylic adjective Pertaining to, derived from, or containing, pentyl; as, pentylic alcohol

Penuchle, Pinocle noun A game at cards, played with forty-eight cards, being all the cards above the eight spots in two packs.

Penult noun [ Abbreviated from penultima .] (Gram. & Pros.) The last syllable but one of a word; the syllable preceding the final one.

Penultima noun [ Latin (sc. syllaba ), from penultimus , paenultimus , the last but one; paene almost + ultimus the last.] Same as Penult .