in·fec·tious 
/ɪnˈfɛkʃəs/ adjective
/ɪnˈfɛkʃəs/ adjective 1 a : capable of causing infection
▪ viruses and other infectious agents
b [more infectious; most infectious] : capable of being passed to someone else by germs that enter the body
▪ an acute infectious illness ▪ a highly infectious disease — compare contagious
c : suffering from a disease that can be spread to other people by germs
▪ an infectious patient 2 [more infectious; most infectious] : capable of being easily spread to other people
▪ Their enthusiasm was infectious. [=contagious] ▪ She has an infectious grin. ▪ infectious laughter
▪ viruses and other infectious agents
b [more infectious; most infectious] : capable of being passed to someone else by germs that enter the body
▪ an acute infectious illness ▪ a highly infectious disease — compare contagious
c : suffering from a disease that can be spread to other people by germs
▪ an infectious patient
▪ Their enthusiasm was infectious. [=contagious] ▪ She has an infectious grin. ▪ infectious laughter
— in·fec·tious·ly adverb
▪ infectiously cheerful/enthusiastic
▪ infectiously cheerful/enthusiastic
