Dictionary.com noun, plural Trinities for 2, 4. 1. Also called Blessed Trinity, Holy Trinity. the union of three persons (Father, Son, and Holy Ghost) in one Godhead, or the three-fold personality of the one Divine Being. 2. a representation of this in art. 3. Trinity Sunday. 4. (lowercase) a group of three; triad. 5. (lowercase) the state of being threefold or triple. Etymonline.com early 13c., "the Father, Son and Holy Spirit," constituting one God in prevailing Christian doctrine, from Old French trinite "Holy Trinity" (11c.), from Late Latin trinitatem (nominative trinitas) "Trinity, triad" (Tertullian), from Latin trinus "threefold, triple," from plural of trini "three at a time, threefold," related to tres (neuter tria) "three" (see three). The Latin word was … Continue reading The Trinity