Breadcrumb Home > Dictionary > Index B bluefin tuna: Meaning and Definition of Find definitions for: blue'fin tu'na Pronunciation: (bl'fin"), [key] a large tuna, Thunnus thynnus, common in temperate seas. See illus. under Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Bluefields bluefish ✖ Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language