'Swordtail' definitions:

Definition of 'swordtail'

noun

Freshwater fish of Central America having a long swordlike tail; popular aquarium fish [syn: swordtail, helleri, topminnow, Xyphophorus helleri]

From: GCIDE

Swordtail \Sword"tail`\, n. (Zool.) (a) The limulus. (b) Any hemipterous insect of the genus Uroxiphus, found upon forest trees. [1913 Webster]