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. [1913 Webster]

2. (Bot.) Having four prominent longitudinal angles. [1913 Webster]

3. (Crystallog.) Designating, or belonging to, a certain system of crystallization; dimetric. See Tetragonal system, under Crystallization. [1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

tetragonal adj : of or relating to or shaped like a quadrilateral

Source: WordNet (r) 2.0
 

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.

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

Source: Webster's Revised Unabridged Dictionary (1913)