/ Dictionary / Index B bilayer: Meaning and Definition of Find definitions for: bi•lay•er Pronunciation: (bī'lā"ur), [key] — n. Biochem. a structure composed of two molecular layers, esp. of phospholipids in cellular membranes. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. bilateral symmetry Bilbao Related Content Daily Word Quiz: hedonist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language