human papillomavirus (HPV), any of a subgroup of viruses belonging to the family Papovaviridae that infect humans, causing warts (papillomas) and other benign tumours as well as cancers of the genital tract, especially of the uterine cervix in women. They are small polygonal viruses containing circular double-stranded DNA (deoxyribonucleic acid); more than 100 distinct types of HPVs have been identified by DNA analysis. Skin warts are of two types—flat warts (which are superficial and usually...