/sayl"fish'/ , n. , pl. ( esp. collectively ) sailfish , ( esp. referring to two or more kinds or species ) sailfishes .
1. a large tropical and subtropical marine fish, Istiophorus platypterus, of the family Istiophoridae, distinguished by a long, high dorsal fin, long pelvic fins, and a double keel on each side of the tail.
2. any of several related fishes having a high dorsal fin.
[ 1585-95; SAIL + FISH ]