A host plant is a living plant attacked by or harboring a parasite or pathogen and from which the invader obtains part or all of its nourishment.
Etymology. "person who receives guests," c.1290, from O.Fr. hoste "guest, host" (12c.), from L. hospitem (nom. hospes) "guest, host," lit. "lord of strangers," from PIE *ghostis- "stranger" (cf. O.C.S. gospodi "lord, master," Goth. gasts, O.E. gæst "guest"). The biological sense of "animal or plant having a parasite " is from 1857. The verb is 1421, from the noun. Hostess is attested from c.1290.