host¹ / hōst/ • n. 1. a person who receives or entertains other people as guests: a dinner-party host. ∎  a person, place, or organization that holds and organizes an event to which others are invited: Innsbruck once played host to the Winter Olympics. ∎  an area in which particular living things are found: Australia is host to some of the world's most dangerous animals. ∎ often humorous the landlord or landlady of a pub: mine host raised his glass of whiskey. ∎  the moderator or emcee of a television or radio program.2. Biol. an animal or plant on or in which a parasite or commensal organism lives. ∎  (also host cell) a living cell in which a virus multiplies. ∎  a person whose immune system has been invaded by a pathogenic organism. ∎  a person or animal that has received transplanted tissue or a transplanted organ.3. (also host computer) a computer that mediates multiple access to databases mounted on it or provides other services to a computer network.• v. [tr.] act as host at (an event) or for (a television or radio program). ∎  [intr.] act as host.host² • n. (a host of or hosts of) a large number of people or things: a host of memories rushed into her mind. ∎ archaic an army. ∎ poetic/lit. (in biblical use) the sun, moon, and stars: the starry host of heaven. ∎ another term for heavenly host. See also Lord of hosts at lord.host³ • n. (usu. the Host) the bread consecrated in the Eucharist: the elevation of the Host.