I. ˈtrīn 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 trine astrological aspect of two celestial bodies