any of a large family (Picornaviridae) of RNA viruses affecting animals, including the enteroviruses and rhinoviruses
See picornavirus in American Heritage Dictionary 4
(pē-kôrˈnə-vīˌrəs, pĭ-)
nounpl.pi·cor·na·vi·rus·es
Any of a group of very small viruses, including the enteroviruses and the rhinoviruses, that infect animals and consist of RNA surrounded by an icosahedral protein shell.