What does contagiously mean?
"Contagiously" is an adverb describing something that spreads from one person to another, whether literally through physical transmission of a disease or figuratively through the rapid, almost irresistible transfer of emotion or behaviour. Its medical sense — as when a virus spreads contagiously through a population — is precise and clinical, but everyday usage overwhelmingly favours the figurative sense: laughter, smiles, panic, and enthusiasm are all commonly described as spreading contagiously. The word derives from "contagion", ultimately from Latin "contagio", meaning contact or touching, reflecting the ancient understanding that many illnesses pass by touch. Because the figurative sense typically attaches to pleasant or energetic things, the word often carries a warm, vivid connotation, making it a favourite of journalists and writers describing collective moods. It pairs naturally with verbs like laugh, smile, and spread.
adverbIn a manner that spreads from person to person by contact or close proximity. By extension, in a way that spreads rapidly and irresistibly to others, as with emotions, laughter, or enthusiasm.
- (Of a disease or pathogen) spreading from person to person by direct or indirect contact.
- (Of emotions, laughter, behaviour, or attitudes) spreading quickly and irresistibly among people.
"She laughed so contagiously that the whole room soon joined in."
"Measles is one of the most contagiously transmitted diseases known."
"He grinned so contagiously that strangers on the train began smiling too."
Laughter really is contagious — studies show hearing someone laugh activates the same brain regions as laughing yourself, which is why we laugh 'contagiously' even at jokes we don't get.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of contagiously
"Contagiously" comes from "contagious", formed from Latin "contagiosus", itself derived from "contagio" meaning contact or infection, from "contingere" (to touch closely), built on "tangere" (to touch). English adopted "contagious" in the 14th century in the sense of communicable disease, and the adverb followed later. Cognates sharing the tangere root include "contact", "tangible", and "contiguous", all preserving the core idea of touching or closeness.
Related word forms
How contagiously is actually used
The word carries a largely neutral-to-positive connotation today: while its medical sense is clinical and negative (describing the spread of illness), it is most frequently used figuratively for desirable qualities such as laughter, optimism, and enthusiasm. It modifies verbs and adjectives ('spread contagiously', 'contagiously cheerful') rather than nouns.
Easily confused with contagiously
Both mean 'spreading readily', but 'contagiously' derives from contagion (transmission by contact) and is the more natural choice for literal disease spread, while 'infectiously' leans toward figurative, positive contexts like charm or energy.