Latin, meaning “for a special purpose." A company may appoint members to an ad hoc committee to study methods that will reduce the firm's energy costs. The ad hoc committee is dissolved when the charge is completed.
Meaning "to this" in Latin, it refers to dealing with situations as they occur rather than ones that are repeated on a regular basis. For example, an "ad hoc query" is a question made up on the spot. An "ad hoc mobile network" is a communications network in which each node participates based on its location at the moment. See ad hoc query, ad hoc mode and mobile ad hoc network.
For the special purpose or end at hand; also, by extension, improvised or impromptu. The term, Latin for “to this,” is most often used for committees established for a specific purpose, as in The committee was formed ad hoc to address health insurance problems. The term is also used as an adjective (An ad hoc committee was formed), and has given rise to the noun adhocism for the tendency to use temporary, provisional, or improvised methods to deal with a particular problem. [Early 1600s]