any of a group of slowly acting viruses that includes the human immunodeficiency virus (HIV), which causes AIDS
Word origin
C20: from Latin lentus slow + virus
lentivirus in American English
(ˈlɛntɪˌvaɪrəs)
noun
any of a genus (Lentivirus) of retroviruses that have a slow but persistent rate of replication and cause various chronic, progressive diseases in hoofed animals, esp. sheep