word-forming element meaning "three, having three, once every three," from Latin tres (neuter tria) or Greek treis, trias "three" (see three).
perfecta n.
method of betting in which the bettor must pick the first- and second-place finishers in correct order, 1971, from American Spanish perfecta, shortened from quiniela perfecta "perfect quiniela," a bet in horseracing (see quinella); for perfecta, see perfect (adj.).