noun, plural ( especially collectively ) kil·li·fish ( especially referring to two or more kinds or species ) kil·li·fish·es. 1.any of several small, oviparous cyprinodont fishes, especially of the genus Fundulus, found in salt, brackish, and fresh waters.
2.any of several livebearers.
Origin: 1805–15, Americanism; perhaps
kill2 +
-i- (unexplained) +
fish