INFEC'TIOUS, adjective Having qualities that may taint, or communicate disease to; as an infectious fever; infectious clothing; infectious air; infectious miasma. 1. Corrupting; tending to taint by communication; as infectious vices or manners. 2. Contaminating with illegality; exposing to seizure and forfeiture. Contraband articles are said to be of an infectious nature. 3. Capable of being communicated by near approach. Grief as well as joy is infectious
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI