/ Dictionary / Index T threadfish: Meaning and Definition of Find definitions for: thread•fish Pronunciation: (thred'fish"), [key] — pl. -fish, -fish•es. any of several jacks of the genus Alectis, esp. A. ciliaris, having the front rays of the dorsal and anal fins greatly elongated. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: threadfish (Thesaurus) threadfin thread-legged bug Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language