[ 'vʌɪrəs ]
■ noun
1》 a submicroscopic infective particle, typically consisting of nucleic acid coated in protein, which can multiply only within the cells of a host organism.
↘an infection or disease caused by such an agent.
2》 (also computer ~ ) a piece of code surreptitiously introduced into a system in order to corrupt it or destroy data.
Origin
ME (denoting snake venom): from L., lit. 'slimy liquid, poison'.