| tetragon | 1. <geometry> A plane figure having four sides and angles; a quadrangle, as a square, a rhombus, etc. 2. <astronomy> 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. Origin: L. Tetragonum, Gr.; (see Tetra-) + corner, angle: cf. F. Tetragone. Source: Websters Dictionary (01 Mar 1998) |
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| trigonum lumbale | An area in the posterior abdominal wall bounded by the edges of the latissimus dorsi and external oblique muscles and the iliac crest; herniations occasionally occur here. Synonym: trigonum lumbale, Petit's lumbar triangle. (05 Mar 2000) |