(1):

(a.) Having four prominent longitudinal angles.

(2):

(a.) Of or pertaining to a tetragon; having four angles or sides; thus, the square, the parallelogram, the rhombus, and the trapezium are tetragonal fingers.

(3):

(a.) Designating, or belonging to, a certain system of crystallization; dimetric. See Tetragonal system, under Crystallization.