/ Dictionary / Index B brainfag: Meaning and Definition of Find definitions for: brain•fag Pronunciation: (brān'fag"), [key] — n. Informal. prolonged mental fatigue. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Brainerd brain fever Related Content Daily Word Quiz: heifer Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language