virus

/ˈvaɪɹəs/noun

A tiny germ, much smaller than bacteria, that gets into living cells and causes diseases such as colds and flu.

Example sentences

“The flu virus spreads easily in crowded places.”
“Antibiotics do not work against a virus.”
“Scientists are studying how the virus attacks the lungs.”

People also say 'I have a virus' to mean a mild illness. In computing, a virus is a harmful program that copies itself.

health technology

Often confused with virus

virus vs bacteria: bacteria (noun): Very small living things, each made of a single cell, found almost everywhere; some cause disease and others are helpful.

Related words

outbreakThe sudden start or rapid spread of something unpleasant, such as a disease.germA tiny living thing, such as a bacterium or virus, that can cause illness.pandemicA disease that spreads across many countries and infects a very large share of the population.diseaseA condition that makes a person, animal, or plant unwell or stops it working properly, unlike an injury, which usually happens in an instant.epidemicAn outbreak of disease that spreads rapidly and affects large numbers of people at the same time.chronicLasting for a long time or coming back again and again, used of problems or illnesses.