In-fĕc'tioŭs, a.
(-fĕk'shus), a. [Fr. infectieux, infectueux.]
Sense 1. Having qualities that may infect; pestilential; as, an infectious fever; infectious clothing; infectious air; infectious vices or manners.
In a house Where the infectious pestilence did reign. Shak.
Sense 2. Corrupting, or tending to corrupt or contaminate; vitiating.
It [the court] is necessary for the polishing of manners ... but it is infectious even to the best morals to live always in it. Dryden.
Sense 3. (Law.) Contaminating with illegality; exposing to seizure and forfeiture.
Contraband articles are said to be of an infectious nature. Kent.
Sense 4. Capable of being easily diffused or spread; readily communicated; as, infectious mirth.
Syn.—See CONTAGIOUS.