/ Dictionary / Index F Fresnel mirrors: Meaning and Definition of Find definitions for: Fresnel' mir'rors Pronunciation: [key] — Optics. Optics. two plane mirrors joined together in a way that makes them useful for studying interference patterns. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Fresnel lens Fresno Related Content Daily Word Quiz: clairvoyant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language