The Perfecta is a wager in which the first two finishers in a race, in exact order of finish, must be picked. It is also known as the Exacta, or the Exactor in Canada.

a bet that you can pick the first and second finishers in the right order

In horse racing, a wager in which the player selects the two horses in a race to finish in 1st and 2nd places in exact order. See "Exacta" or "Exactor"