- Easily passed on - Having qualities that may infect; communicable or
caused by infection; pestilential; epidemic; as, an infectious fever;
infectious clothing; infectious air; infectious vices. - Corrupting, or tending to corrupt or contaminate;
vitiating; demoralizing. - Contaminating with illegality; exposing to seizure and
forfeiture. - Capable of being easily diffused or spread;
sympathetic; readily communicated; as, infectious mirth.