In 1973 Architects and theorists Charles Jencks and Nathan Silver wrote Adhocism: The Case for Improvisation. Jencks coined the term in 1968.
"It can be applied to many human endeavours, denoting a principle of action having speed or economy and purpose or utility. Basically it involves using an available system or dealing with an existing situation in a new way to solve a problem quickly and effectively. It is a method of creation relying particularly on resources which are already at hand."
Credit: Scan of cover, Adhocism