pro·vi·rus 
(prōvī′rəs, prō-vī-)
(prōvī′rəs, prō-vī-)n. pl. pro·vi·rus·es
A form of a virus that allows it to be integrated into the genome of a host cell and to replicate in concert with the cell's genetic material without causing cell lysis.
provi′ral (-rəl) adj.