Merriam-Webster Collegiate Dictionary - trine

 I. adjective  Etymology: Middle English, from Anglo-French trin, from Latin trinus, from trini three each; akin to Latin tres three — more at three  Date: 14th century  1. threefold, triple  2. of, relating to, or being the favorable astrological aspect of two celestial bodies 120 degrees apart  II. noun  Date: 1552  1. a group of three ; triad  2. the ~ astrological aspect of two celestial bodies