Emily Dickinson Lexicon

TET'RA-GON, n. [Gr. τετραγωνος; τετρα, for τεσσαρες, four, and γωνια, an angle.]

1. In geometry, a figure having four angles; a quadrangle; as a square, a rhombus, &c.
2. In astrology, 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.