Breadcrumb Home > Dictionary > Index K knucklehead: Meaning and Definition of Find definitions for: knuck•le•head Pronunciation: (nuk'ul-hed"), [key] — n. Informal. a stupid, bumbling, inept person. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: knucklehead (Thesaurus) knuckle-duster knuckle joint ✖ Related Content Daily Word Quiz: glissade Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language