/ Dictionary / Index C contactant: Meaning and Definition of Find definitions for: con•tac•tant Pronunciation: (kun-tak'tunt), [key] — n. Med. any substance that might induce an allergy by coming in contact with the skin or a mucous membrane. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. contact contact binary 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