/ Dictionary / Index C crackbrained: Meaning and Definition of Find definitions for: crack•brained Pronunciation: (krak'brānd"), [key] — adj. foolish, senseless, or insane. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: crackbrained (Thesaurus) crackbrain crackdown Related Content Daily Word Quiz: jaundice Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language