Definition of “infectious” - English Dictionary

british dictionary

“infectious” in British English

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infectiousadjective

uk /ɪnˈfek.ʃəs/ us /ɪnˈfek.ʃəs/

C2 (of a disease) able to be passed one person, animal, or plant to another:

an infectious disease

C2 able to pass a disease from one person, animal, or plant to another:

an infectious patient
After the 21-day isolation period, Ebola survivors are no longer infectious.

C2 Something that is infectious has an effect on everyone who is present and makes them want to join in:

an infectious laugh
infectious enthusiasm

(Definition of “infectious” from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

“infectious” in American English

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infectiousadjective [ not gradable ]

us /ɪnˈfek·ʃəs/

able to infect someone:

infectious diseases

If something is infectious, it quickly spreads or influences others:

an infectious laugh

(Definition of “infectious” from the Cambridge Academic Content Dictionary © Cambridge University Press)