Tetrad
(Tet"rad) n. [L. tetras, - adis, Gr. : cf. F. tétrade.]
1. The number four; a collection of four things; a quaternion.
2. (Chem.) A tetravalent or quadrivalent atom or radical; as, carbon is a tetrad.
Tetradactyl
(Tet`ra*dac"tyl, Tet`ra*dac"tyle) a. [Cf. F. tétradactyle.] (Zoöl.) Tetradactylous.
Tetradactylous
(Tet`ra*dac"tyl*ous) a. [Gr. te`tra- (see Tetra-) + finger, toe.] (Zoöl.) Having, or characterized
by, four digits to the foot or hand.
Tetradecane
(Tet`ra*dec"ane) n. [Tetra- + Gr. ten.] (Chem.) A light oily hydrocarbon, C14H30, of the
marsh-gas series; — so called from the fourteen carbon atoms in the molecule.
Tetradecapoda
(||Tet`ra*de*cap"o*da) n. pl. [NL. See Tetra-, and Decapoda.] (Zoöl.) Same as Arthrostraca.
Tetradic
(Tet*rad"ic) a. (Chem.) Of or pertaining to a tetrad; possessing or having the characteristics of
a tetrad; as, a carbon is a tetradic element.
Tetradite
(Tet"ra*dite) n. [See Tetrad.] A person in some way remarkable with regard to the number
four, as one born on the fourth day of the month, or one who reverenced four persons in the Godhead.
Smart.
Tetradon
(Tet"ra*don) n. (Zoöl.) See Tetrodon.
Tetradont
(Tet"ra*dont) a. & n. (Zoöl.) See Tetrodont.
Tetradrachm
(Tet"ra*drachm ||Tet`ra*drach"ma) n. [NL. tetradrachma, fr. Gr. tetra`drachmon; te`tra-
(see Tetra-) + drachmh` drachm, drachma.] A silver coin among the ancient Greeks, of the value of
four drachms. The Attic tetradrachm was equal to 3s. 3d. sterling, or about 76 cents.
Tetradymite
(Tet*rad"y*mite) n. [Gr. tetra`dymos fourfold. So named from its occurrence in compound
twin crystals, or fourlings.] (Min.) A telluride of bismuth. It is of a pale steel-gray color and metallic
luster, and usually occurs in foliated masses. Called also telluric bismuth.
Tetradynamia
(||Tet`ra*dy*na"mi*a) n. pl. [NL., fr. Gr. te`tra- (see Tetra-) + power.] (Bot.) A Linnæan
class of plants having six stamens, four of which are longer than the others.
Tetradynamian
(Tet`ra*dy*na"mi*an) n. (Bot.) A plant of the order Tetradynamia.
Tetradynamian
(Tet`ra*dy*na"mi*an Tet`ra*dyn"a*mous) a. (Bot.) Belonging to the order Tetradynamia; having
six stamens, four of which are uniformly longer than the others.
Tetragon
(Tet"ra*gon) n. [L. tetragonum, Gr. tetra`gwnon; te`tra- (see Tetra-) + gwni`a corner, angle: cf.
F. tétragone.]
1. (Geom.) A plane figure having four sides and angles; a quadrangle, as a square, a rhombus, etc.
2. (Astrol.) An aspect of two planets with regard to the earth when they are distant from each other
ninety degrees, or the fourth of a circle. Hutton.
Tetragonal
(Te*trag"o*nal) a.
1. (Geom.) Of or pertaining to a tetragon; having four angles or sides; thus, the square, the parallelogram,
the rhombus, and the trapezium are tetragonal fingers.
2. (Bot.) Having four prominent longitudinal angles.
