3. (Crystallog.) Designating, or belonging to, a certain system of crystallization; dimetric. See Tetragonal
system, under Crystallization.
Tetragrammaton
(||Tet`ra*gram"ma*ton) n. [NL., fr. Gr. te`tra- (see Tetra-) + a letter.] The mystic
number four, which was often symbolized to represent the Deity, whose name was expressed by four
letters among some ancient nations; as, the Hebrew JeHoVaH, Greek qeo`s, Latin deus, etc.
Tetragynia
(||Tet`ra*gyn"i*a) n. pl. [NL., fr. Gr. te`tra- (see Tetra-) + gynh` a woman, female.] (Bot.)
A Linnæan order of plants having four styles.
Tetragynian
(Tet`ra*gyn"i*an Te*trag"y*nous) a. (Bot.) Belonging to the order Tetragynia; having four
styles.
Tetrahedral
(Tet`ra*he"dral) a. [See Tetrahedron.]
1. Having, or composed of, four sides.
2. (Crystallog.) (a) Having the form of the regular tetrahedron. (b) Pertaining or related to a tetrahedron,
or to the system of hemihedral forms to which the tetrahedron belongs.
Tetrahedral angle (Geom.), a solid angle bounded or inclosed by four plane angles.
Tetrahedrally
(Tet`ra*he"dral*ly), adv. In a tetrahedral manner.
Tetrahedrite
(Tet`ra*he"drite) n. [So called because the crystals of the species are commonly tetrahedrons.]
(Min.) A sulphide of antimony and copper, with small quantities of other metals. It is a very common ore
of copper, and some varieties yield a considerable presentage of silver. Called also gray copper ore,
fahlore, and panabase.
Tetrahedron
(Tet`ra*he"dron) n. [Tetra- + Gr. seat, base, fr. to sit.] (Geom.) A solid figure inclosed or
bounded by four triangles.
In crystallography, the regular tetrahedron is regarded as the hemihedral form of the regular octahedron.
Regular tetrahedron (Geom.), a solid bounded by four equal equilateral triangles; one of the five regular
solids.
Tetrahexahedral
(Tet`ra*hex`a*he"dral) a. (Crystallog.) Pertaining to a tetrahexahedron.
Tetrahexahedron
(Tet`ra*hex`a*he"dron) n. [Tetra- + hexahedron.] (Crystallog.) A solid in the isometric
system, bounded by twenty-four equal triangular faces, four corresponding to each face of the cube.
Tetrakishexahedron
(Tet`ra*kis*hex`a*he"dron) n. [Gr. four times + E. hexahedron.] (Crystallog.) A
tetrahexahedron.
Tetrakosane
(Tet"ra*ko*sane`) n. [Tetra- + Gr. twenty.] (Chem.) A hydrocarbon, C24H50, resembling
paraffin, and like it belonging to the marsh-gas series; — so called from having twenty-four atoms of
carbon in the molecule.
Tetralogy
(Te*tral"o*gy) n. [Gr. te`tra- (see Tetra-) + a speech, discourse: cf. F. tétralogie.] (Gr. Drama)
A group or series of four dramatic pieces, three tragedies and one satyric, or comic, piece (or sometimes
four tragedies), represented consequently on the Attic stage at the Dionysiac festival.
A group or series of three tragedies, exhibited together without a fourth piese, was called a trilogy.
