ad hoc
From Longman Dictionary of Contemporary Englishad hocad hoc /æd ˈhɒk◂ $ -ˈhɑːk◂, -ˈhoʊk◂/ adjective, adverb formal not planned, but arranged or done only when necessaryad hoc committee/group etc decisions made on an ad hoc basisExamples from the Corpusad hoc• An ad hoc committee has been set up to deal with the problem.on an ad hoc basis• In contrast to the Lisa approach, the Macintosh team implemented its interface issues on an ad hoc basis.Origin ad hoc (1600-1700) Latin “for this”