Webster's Revised Unabridged Dictionary · 1913

Tetragonal

Tetragonal , adjective

1.
(Geometry) 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.
(Botany) Having four prominent longitudinal angles.
3.
(Crystallography) Designating, or belonging to, a certain system of crystallization; dimetric. See Tetragonal system, under Crystallization.