/ Dictionary / Index B bilateral symmetry: Meaning and Definition of Find definitions for: bilat'eral sym'metry Pronunciation: [key] — Biol. Biol. a basic body plan in which the left and right sides of the organism can be divided into approximate mirror images of each other along the midline. Cf. radial symmetry. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. bilateral bilayer 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