/ Dictionary / Index B brown fat: Meaning and Definition of Find definitions for: brown' fat' Pronunciation: [key] brownish-yellow adipose tissue in the upper back, or interscapular, region of many mammals, most conspicuously in hibernating species, composed of numerous innervated fat cells that can produce heat during cold stress; thermogenic tissue. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. brown-eyed Susan Brownfield Related Content Daily Word Quiz: sinister Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language