ad hoc

The Latin phrase ad hoc translates as “toward this”, and is used in mathematics to describe anything that has been made up specifically for one particular purpose.

Examples

1. an ad hoc definition is a temporary definition that mightbe useful for the discussion at hand. For instance, let a nice setbe a closed set with smooth boundary.

2. If a proof makes use of an ad hoc construction, the proof(typically) does not make use of a general theory for the problem.

See alsohttp://en.wikipedia.org/wiki/Ad_hocArticle on ad hoc on Wikipedia