Main Entry: in·fec·tious

Pronunciation: \-shəs\

Function: adjective

Date: 1542

1 a : capable of causing infection <viruses and other infectious agents> b : communicable by infection <an infectious disease> — compare contagious
2 : that corrupts or contaminates
3 : spreading or capable of spreading rapidly to others <their enthusiasm was infectious> <an infectious grin>

— in·fec·tious·ly adverb

— in·fec·tious·ness noun