Term: tumor virus: a cell-free filtrate held to be a virus responsible for a specific neoplasm
Broader: virus: (virology) ultramicroscopic infectious agent that replicates itself only within cells of living hosts; many are pathogenic; a piece of nucleic acid (DNA or RNA) wrapped in a thin coat of protein | Unrelated: leather flower: woody vine of the southern United States having purple or blue flowers with leathery recurved sepals