Tĕt'ra-gŏn, n.

n. [Fr. tétragone, Lat. tetragonum, Gr. τετράγωνον, from τέτρα, four, and γωνία, corner, angle.] 1. (Geom.) A plane figure having four angles; a quadrangle, as a square, a rhombus, and the like. Tetragons. (Geom.) 2. (Astrol.) 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. Hutton.