/ Dictionary / Index I infectious: Meaning and Definition of Find definitions for: in•fec•tious Pronunciation: (in-fek'shus), [key] — adj. communicable by infection, as from one person to another or from one part of the body to another: infectious diseases. causing or communicating infection. tending to spread from one to another: infectious laughter. capable of contaminating with illegality; exposing to seizure or forfeiture. diseased. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: infectious (Thesaurus) infection infectious anemia of horses 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