/ Dictionary / Index B brainless: Meaning and Definition of Find definitions for: brain•less Pronunciation: (brān'lis), [key] — adj. mentally weak; foolish; witless; stupid. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: brainless (Thesaurus) brainish brainpan Related Content Daily Word Quiz: blanch Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language