/ Dictionary / Index M membrane: Meaning and Definition of Find definitions for: mem•brane Pronunciation: (mem'brān), [key] — n. a thin, pliable sheet or layer of animal or vegetable tissue, serving to line an organ, connect parts, etc. the thin, limiting covering of a cell or cell part. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: membrane (Thesaurus) membership membrane bone Related Content Daily Word Quiz: nonchalant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language