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.
Py*ram"i*dal (?), n. (Anat.) One of the carpal bones. See Cuneiform,
n., 2 (b).
Py*ram"i*dal*ly, adv. Like a pyramid.
{ Pyr`a*mid"ic (?), Pyr`a*mid"ic*al (?), } a. 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, adv. Pyr`a*mild"ic*al*ness, n.
||Pyr`a*mid"i*on (?), n.; pl. Pyramidia (#). [NL., from L. pyramis. See
||Pyramid.] The small pyramid which crowns or completes an obelisk.
Py*ram"i*doid (?), n. [Gr. &?;, &?;, pyramid + -id: cf. F.
pyramidoÔde.] A solid resembling a pyramid; -- called also pyramoid.
Barlow.
||Pyr"a*mis (?), n.; pl. Pyramides (#). [L.] A pyramid.
Pyr"a*moid (?), n. See Pyramidoid.
Py*rar"gy*rite (?), n. [Gr. &?; 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.
Pyre (?), n. [L. pure, Gr. &?;, fr. &?; 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.
||Py*re"na (?), n.; pl. PyrenÊ (#). [NL., fr. Gr. &?;, the stone of
||fruit.] (Bot.) A nutlet resembling a seed, or the kernel of a drupe.
||Gray.
Py"rene (?), n. [Gr. &?; fire.] (Chem.) One of the less volatile
hydrocarbons of coal tar, obtained as a white crystalline substance,
C16H10.
Py"rene, n. (Bot.) Same as Pyrena.
Pyr`e*ne"an (?), a. [L. Pyrenaei (sc. montes) the Pyrenees, fr. Pyrene,
Gr.&?; 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. -- n. The Pyrenees. Shak.
Py*re"noid (?), n. [Gr. &?; like a kernel. See Pyrena, and -oid.]
(Zoˆl.) A transparent body found in the chromatophores of certain
Infusoria.
Pyr"eth*rin (?), n. [NL. Pyrethrum, generic name of feverfew, Gr. &?;
feverfew.] (Chem.) A substance resembling, and isomeric with, ordinary
camphor, and extracted from the essential oil of feverfew; -- called
also Pyrethrum camphor.
Pyr"eth*rine (?), n. (Chem.) An alkaloid extracted from the root of the
pellitory of Spain (Anacyclus pyrethrum).
Py*ret"ic (?), a. [Gr. &?; burning heat, fever, from &?; fire: cf. F.
pyrÈtique.] (Med.) Of or pertaining to fever; febrile.
Pyr`e*tol"o*gy (?), n. [Gr. &?; fever + -logy: cf. F. pyrÈtologie.]
(Med.) A discourse or treatise on fevers; the doctrine of fevers.
Hooper.
||Py*rex"i*a (?), n.; pl. PyrexiÊ (#). [NL., fr. Gr. &?; to be
||feverish, akin to &?; fever.] (Med.) The febrile condition.
{ Py*rex"i*al (?), Py*rex"ic*al (?), } a. (Med.) Of or pertaining to
fever; feverish.
Pyr"gom (?), n. [Gr. &?; a place furnished with towers, fr. &?; a
tower.] (Min.) A variety of pyroxene; -- called also fassaite.
Pyr*he`li*om"e*ter (?), n. [Gr. &?; fire + &?; sun + -meter.] (Physics)
An instrument for measuring the direct heating effect of the sun's
rays.
Py*rid"ic (?), a. (Physiol. Chem.) Related to, or formed from, pyridin
or its homologues; as, the pyridic bases.
Pyr"i*dine (?), n. [From Gr. &?; fire.] (Physiol. Chem.) A nitrogenous
base, C5H5N, 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 ptomaÔnes, may be mentioned. See Lutidine.
Pyr"i*dyl (?), n. [Pyridine + -yl.] (Chem.) A hypothetical radical,
C5H4N, regarded as the essential residue of pyridine, and analogous to
phenyl.
Pyr"i*form (?), a. [L. pyrum, pirum, a pear + -form: cf. F. pyriforme,
piriforme.] Having the form of a pear; pear- shaped.
Pyr`i*ta"ceous (?), a. (Min.) Of or pertaining to pyrites. See Pyritic.
Pyr"ite (?), n.; pl. Pyrites (#). [Cf. F. 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.
Py*ri"tes (?), n. [L., fr. Gr. &?;, fr. &?; 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.
{ Py*rit"ic (?), Py*rit"ic*al (?), } a. (Min.) Of or pertaining to
pyrites; consisting of, or resembling, pyrites.
Pyr`i*tif"er*ous (?), a. [Pyrites + -ferous.] (Min.) Containing or
producing pyrites.
Pyr"i*tize (?), v. t. [Cf. F. pyritiser.] To convert into pyrites.
Pyr`i*to*he"dral (?), a. [See Pyritohedron.] (Crystallog.) Like pyrites
in hemihedral form.
Pyr`i*to*he"dron (?), n. [Pyrite + Gr. &?; base.] (Crystallog.) The
pentagonal dodecahedron, a common form of pyrite.