/ Dictionary / Index R rattlebrain: Meaning and Definition of Find definitions for: rat•tle•brain Pronunciation: (rat'l-brān"), [key] — n. a giddy, empty-headed, talkative person. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. rattle rattlebrained Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language