/ Dictionary / Index C contact binary: Meaning and Definition of Find definitions for: con'tact bi"nary Pronunciation: [key] — Astron. Astron. a binary system in which the envelopes of gas surrounding each star are in contact. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. contactant contact cement Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language