Webster's Dictionary, 1913

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Pyoxanthose noun [ Greek ... pus + ... yellow.] (Physiol. (Chemistry) A greenish yellow crystalline coloring matter found with pyocyanin in pus.

Pyracanth noun [ Greek ... fire + ... a thorn, prickly plant.] (Botany) The evergreen thorn ( Cratægus Pyracantha ), a shrub native of Europe.

Pyral adjective Of or pertaining to a pyre. [ R.]

Pyralid noun [ Latin pyralis , -idis , a kind of winged insect.] (Zoology) Any moth of the family Pyralidæ . The species are numerous and mostly small, but some of them are very injurious, as the bee moth, meal moth, hop moth, and clover moth.

Pyramid noun [ Latin pyramis , -idis , from Greek ..., ..., of Egyptian origin: confer French pyramide .]


1. A solid body standing on a triangular, square, or polygonal base, and terminating in a point at the top; especially, a structure or edifice of this shape.

2. (Geom.) A solid figure contained by a plane rectilineal figure as base and several triangles which have a common vertex and whose bases are sides of the base.

3. plural (Billiards) The game of pool in which the balls are placed in the form of a triangle at spot. [ Eng.]

Altitude of a pyramid (Geom.) , the perpendicular distance from the vertex to the plane of the base. -- Axis of a pyramid (Geom.) , a straight line drawn from the vertex to the center of the base. -- Earth pyramid . (Geol.) See Earth pillars , under Earth . -- Right pyramid (Geom.) a pyramid whose axis is perpendicular to the base.

Pyramid intransitive verb (Speculation) To enlarge one's holding or interest in a series of operations on a continued rise or decline by using the profits to buy or sell additional amounts on a margin, as where one buys on a 10% margin 100 shares of stock quoted at 100, holds it till it rises to 105, and then uses the paper profit to buy 50 shares more, etc. The series of operations constitutes a pyramid .

Pyramid transitive verb (Speculation) To use, or to deal in, in a pyramiding transaction. See Pyramid , intransitive verb

Pyramid noun (Speculation) The series of operations involved in pyramiding. See Pyramid , intransitive verb

Pyramidal adjective [ Confer French pyramidal .]


1. Of or pertaining to a pyramid; in the form of a a pyramid; pyramidical; as, pyramidal cleavage.

The mystic obelisks stand up
Triangular, pyramidal .
Mrs. Browning.

2. (Crystallog.) Same as Tetragonal .

Pyramidal numbers (Math.) , certain series of figurate numbers expressing the number of balls or points that may be arranged in the form of pyramids. Thus 1, 4, 10, 20, 35, etc., are triangular pyramidal numbers ; and 1, 5, 14, 30, 55, etc., are square pyramidal numbers .

Pyramidal noun (Anat.) One of the carpal bones. See Cuneiform , noun , 2 (b) .

Pyramidally adverb Like a pyramid.

Pyramidic, Pyramidical adjective Of or pertaining to a pyramid; having the form of a pyramid; pyramidal. " A pyramidical rock." Goldsmith. "Gold in pyramidic plenty piled." Shenstone. -- Pyr`a*mid"ic*al*ly , adverb Pyr`a*mild"ic*al*ness , noun

Pyramidion noun ; plural Pyramidia . [ New Latin , from Latin pyramis . See Pyramid .] The small pyramid which crowns or completes an obelisk.

Pyramidoid noun [ Greek ..., ..., pyramid + -id : confer French pyramidoïde .] A solid resembling a pyramid; -- called also pyramoid . Barlow.

Pyramis noun ; plural Pyramides . [ Latin ] A pyramid.

Pyramoid noun See Pyramidoid .

Pyrargyrite noun [ Greek ... fire + ... silver.] (Min.) Ruby silver; dark red silver ore. It is a sulphide of antimony and silver, occurring in rhombohedral crystals or massive, and is of a dark red or black color with a metallic adamantine luster.

Pyrazine noun Also -zin [ Pyr idine + Greek ... not + ... life.] (Org. Chem.) A feebly basic solid, C 4 H 4 N 2 , obtained by distilling piperazine with zinc dust, and in other ways. Also, by extension, any of various derivatives of the same.

Pyre noun [ Latin pure , Greek ..., from ... fire. See Fire .] A funeral pile; a combustible heap on which the dead are burned; hence, any pile to be burnt.

For nine long nights, through all the dusky air,
The pyres thick flaming shot a dismal glare.
Pope.

Pyrena noun ; plural Pyrenæ . [ New Latin , from Greek ..., the stone of fruit.] (Botany) A nutlet resembling a seed, or the kernel of a drupe. Gray.

Pyrene noun [ Greek ... fire.] (Chemistry) One of the less volatile hydrocarbons of coal tar, obtained as a white crystalline substance, C 16 H 10 .

Pyrene noun (Botany) Same as Pyrena .

Pyrenean adjective [ Latin Pyrenaei (sc. monte s) the Pyrenees, from Pyrene , Greek ... a daughter of Bebryx, beloved by Hercules, and buried upon these mountains.] Of or pertaining to the Pyrenees, a range of mountains separating France and Spain. -- noun The Pyrenees. Shak.

Pyrenoid noun [ Greek ... like a kernel. See Pyrena , and -oid .] (Zoology) A transparent body found in the chromatophores of certain Infusoria.

Pyrethrin noun [ New Latin Pyrethrum , generic name of feverfew, Greek ... feverfew.] (Chemistry) A substance resembling, and isomeric with, ordinary camphor, and extracted from the essential oil of feverfew; -- called also Pyrethrum camphor .

Pyrethrine noun (Chemistry) An alkaloid extracted from the root of the pellitory of Spain ( Anacyclus pyrethrum ).

Pyretic adjective [ Greek ... burning heat, fever, from ... fire: confer French pyrétique .] (Medicine) Of or pertaining to fever; febrile.

Pyretology noun [ Greek ... fever + -logy : confer French pyrétologie .] (Medicine) A discourse or treatise on fevers; the doctrine of fevers. Hooper.

Pyrexia noun ; plural Pyrexiæ . [ New Latin , from Greek ... to be feverish, akin to ... fever.] (Medicine) The febrile condition.

Pyrexial, Pyrexical adjective (Medicine) Of or pertaining to fever; feverish.

Pyrgom noun [ Greek ... a place furnished with towers, from ... a tower.] (Min.) A variety of pyroxene; -- called also fassaite .

Pyrheliometer noun [ Greek ... fire + ... sun + -meter .] (Physics) An instrument for measuring the direct heating effect of the sun's rays.

Pyridic adjective (Physiol. Chem.) Related to, or formed from, pyridin or its homologues; as, the pyridic bases.

Pyridine noun [ From Greek ... fire.] (Physiol. Chem.) A nitrogenous base, C 5 H 5 N, obtained from the distillation of bone oil or coal tar, and by the decomposition of certain alkaloids, as a colorless liquid with a peculiar pungent odor. It is the nucleus of a large number of organic substances, among which several vegetable alkaloids, as nicotine and certain of the ptomaïnes, may be mentioned. See Lutidine .

Pyridyl noun [ Pyrid ine + -yl .] (Chemistry) A hypothetical radical, C 5 H 4 N, regarded as the essential residue of pyridine, and analogous to phenyl.

Pyriform adjective [ Latin pyrum , pirum , a pear + -form : confer French pyriforme , piriforme .] Having the form of a pear; pear- shaped.

Pyritaceous adjective (Min.) Of or pertaining to pyrites. See Pyritic .

Pyrite noun ; plural Pyrites . [ Confer French pyrite . See Pyrites .] (Min.) A common mineral of a pale brass- yellow color and brilliant metallic luster, crystallizing in the isometric system; iron pyrites; iron disulphide.

Hence sable coal his massy couch extends,
And stars of gold the sparkling pyrite blends.
E. Darwin.

Pyrites noun [ Latin , from Greek ..., from ... fire. See Pyre .] (Min.) A name given to a number of metallic minerals, sulphides of iron, copper, cobalt, nickel, and tin, of a white or yellowish color.

» The term was originally applied to the mineral pyrite, or iron pyrites, in allusion to its giving sparks when struck with steel.

Arsenical pyrites , arsenopyrite. -- Auriferous pyrites . See under Auriferous . -- Capillary pyrites , millerite. -- Common pyrites , isometric iron disulphide; pyrite. -- Hair pyrites , millerite. -- Iron pyrites . See Pyrite . -- Magnetic pyrites , pyrrhotite. -- Tin pyrites , stannite. -- White iron pyrites , orthorhombic iron disulphide; marcasite. This includes cockscomb pyrites (a variety of marcasite, named in allusion to its form), spear pyrites, etc. -- Yellow , or Copper , pyrites , the sulphide of copper and iron; chalcopyrite.

Pyritic, Pyritical adjective (Min.) Of or pertaining to pyrites; consisting of, or resembling, pyrites.

Pyritiferous adjective [ Pyrites + -ferous .] (Min.) Containing or producing pyrites.

Pyritize transitive verb [ Confer French pyritiser .] To convert into pyrites.

Pyritohedral adjective [ See Pyritohedron .] (Crystallog.) Like pyrites in hemihedral form.

Pyritohedron noun [ Pyrite + Greek ... base.] (Crystallog.) The pentagonal dodecahedron, a common form of pyrite.

Pyritoid noun [ Pyrite + - oid .] (Crystallog.) Pyritohedron. [ R.]

Pyritology noun [ Greek ... of fire + -logy .] The science of blowpipe analysis.

Pyritous adjective Pyritic.

Pyro noun (Photog.) Abbreviation of pyrogallic acid . [ Colloq.]

Pyro-, Pyr- [ Greek ..., ..., fire.] Combining forms designating fire or heat ; specifically (Chemistry) , used to imply an actual or theoretical derivative by the action of heat ; as in pyro phosphoric, pyro sulphuric, pyro tartaric, pyro tungstic, etc.

Pyroacetic adjective [ Pyro- + acetic : confer French pyroacétique .] (Chemistry) Pertaining to, and designating, a substance (acetone) obtained by the distillation of the acetates. It is now called also pyroacetic ether , and formerly was called pyroacetic spirit .