/ Dictionary / Index U underboss: Meaning and Definition of Find definitions for: un•der•boss Pronunciation: (un'dur-bôs", -bos"), [key] — n. a lesser or minor boss, often the second in command, as in an underworld hierarchy. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: underboss (Thesaurus) underbody underbred Related Content Daily Word Quiz: apogee Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language