(biology) A living cell which harbours an infectious agent (such as a virus or bacterium).

(geology) The background mineral material in which the object of study (crystals, fossils, specific minerals, groundwater, etc.) is embedded or through which it travels.

plural of jump host

(computing) Synonym of jump server

(slang, humorous) An exceptional host.

(UK, aviation) A male flight attendant; a steward.

plural of air host

To host an important event or visitor.

plural of host rock

plural of host-rock