noun
perfecta; exacta; straight forecast
A type of bet in horse racing, boat racing, or bicycle racing where the bettor must correctly predict the first two finishers in exact order.
競馬で連勝単式を買うときは、1着と2着を順番通りに当てなければならない。
When you bet a perfecta in horse racing, you must correctly pick the first and second place finishers in the exact order.
連勝複式 (quinella) only requires picking the first two finishers regardless of order, while 連勝単式 requires the exact order.
Compound of 連勝 (consecutive wins) + 単式 (single-entry style), referring to a bet where the exact order of the first two finishers must be predicted.