English: reassortant virus 
Welsh: feirws cyfansawdd
Subject: Iechyd
English definition: A virus with gene segments derived from more than one virus, achieved by co-infection of a single cell by these viruses.. 
Welsh definition: Feirws sy'n gymysgedd o enynnau mwy nag un feirws. Mae hynny fel arfer yn digwydd mewn cell letyol sydd wedi'i heintio gan fwy nag un feirws..