ex·act·a 
(ĭg-zăktə)
(ĭg-zăktə)n.
A method of betting, as on a horserace, in which the bettor must correctly pick those finishing in the first and second places in precisely that sequence. Also called perfecta.
[From American Spanish quiniela exacta, exact quiniela (a game of chance), from Spanish exacta, feminine of exacto, from Latin exāctus; see EXACT.]