Virion

A virion (plural: viria or virions) is an inert virus particle existing exclusively outside of a host cell. A virion may have the capability to invade a cell; viria that lack this capability are termed defective. Upon entering the cell, the non-defective virion disassembles and the genetic material from the virus takes control of the cell infrastructure, thus enabling the virus to replicate. The genetic material (core, either DNA or RNA, along with occasionally present ) inside the virion is usually enclosed in a protection shell, known as the capsid.

While the terms "virus" and "virion" are occasionally confused, recently "virion" is used solely to describe the virus structure outside of cells, while the terms "virus/viral" are broader and also include biological properties such as the infectivity of a virion.