Any member of a group (originally the genus Orthomyxovirus, now the family Orthomyxoviridae) of enveloped, single-stranded RNA viruses which have a segmented genome and two types of glycoprotein (haemagglutinin and neuraminidase) projecting from the envelope, and which include the influenza viruses. Also (in form Orthomyxovirus): the (former) genus itself.
In addition to the influenza viruses, the family Orthomyxoviridae now includes the genera Thogotovirus (containing tick-borne vertebrate viruses) and Isavirus (containing only the infectious salmon anaemia virus).
1970s. From ortho- + myxovirus.