/ Dictionary / Index R restriction site: Meaning and Definition of Find definitions for: restric'tion site" Pronunciation: [key] — Biochem. Biochem. the place on a DNA molecule where a restriction enzyme acts. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. restriction play restrictive Related Content Daily Word Quiz: dissonant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language