Ad hoc
Ad hoc is a Latin phrase meaning "for this". 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 organizations, 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, or a purpose-specific equation.