/ Dictionary / Index R R.N.A.S.: Meaning and Definition of Find definitions for: R.N.A.S. Pronunciation: [key] — Brit. Brit. Royal Naval Air Service. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: rnas (Thesaurus) RNA polymerase RNase Related Content Daily Word Quiz: placid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language