Added 9 October 2026
infectious
/ɪnˈfɛk.ʃəs/ adjective
Latin root: īnfectiōsus Wiktionary
adjective Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about infectious at Wordnik → Where our words come from →
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Caused by an agent that enters the host's body (such as a bacterium, virus, parasite, or prion); often, also, transmitted among hosts via any of various routes (for example, contact, droplet-borne, airborne, waterborne, foodborne, fomite-borne, or bloodborne).
Cancer is usually not infectious.
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Able to infect others; capable of transmitting pathogens.
Despite feeling better, the patient is still infectious.
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Spreading quickly from one person to another.
infectious smile
Origin
Borrowed from New Latin īnfectiōsus. By surface analysis, infect + -ious.
From Wiktionary, via Kaikki.org (CC BY-SA)