/kil"ee fish'/ , n. , pl. ( esp. collectively ) killifish , ( esp. referring to two or more kinds or species ) killifishes .
1. any of several small, oviparous cyprinodont fishes, esp. of the genus Fundulus, found in salt, brackish, and fresh waters.
2. any of several livebearers. Cf. least killifish .
[ 1805-15, Amer.; perh. KILL 2 + -i- (unexplained) + FISH ]