Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “virus”

See all translations

virus

noun [C]  /ˈvɑɪ·rəs/ us  

virus noun [C] (SMALL ORGANISM)

biology a very small organism that causes disease in humans, animals, and plants A virus is also a disease caused by a virus: She’s had a virus for several days.

virus noun [C] (COMPUTER PROBLEM)

a hidden set of instructions in a computer program that is intended to introduce faults into a computer system or cause it to perform actions that were not planned
(Definition of virus from the Cambridge Academic Content Dictionary © Cambridge University Press)
What is the pronunciation of virus?
Add Cambridge dictionaries to your browser to your website

Definitions of “virus” in other dictionaries

Word of the Day

cold snap

a short period of cold weather

Word of the Day

Cleavage proves divisive in Cambridge’s words of 2014

by Alastair Horne,
December 19, 2014
​​​​ Other dictionaries may choose faddish novelties as their words of the year, but here at Cambridge, we like to do something different. We look for the words that have seen sudden surges in searches over the course of the year – words that have been baffling users of English and driven them

Read More 

cinderella surgery noun

December 15, 2014
cosmetic surgery to the feet We have all heard of people having nose jobs, boob jobs and liposuction – but now a new trend growing in popularity in America: Cinderella surgery.

Read More