Ad Hoc in English, it generally signifies a solution designed for a specific problem or task, non-generalizable, and not intended to be able to be adapted to other purposes (compare with a priori).
Common examples are ad hoc committees, and commissions created at the national or international level for a specific task. In other fields, the term could refer, for example, to a military unit created under special circumstances, a tailor-made suit, a handcrafted network protocol (e.g. Ad Hoc network), a temporary banding together of geographically-linked franchise locations (of a given national brand) to issue advertising coupons, or a purpose-specific equation.
Ad Hoc can also be an adjective describing the temporary, provisional, or improvised methods to deal with a particular problem, the tendency of which has given rise to the noun Adhocism.[1] It also could mean shifting contexts to create new meanings or inadequate planning.