monkey patch

Etymology
Apparently from earlier, understood as gorilla patch. A monkey patch was then a more carefully written instance of such a patch. Or simply derived from.

Noun

 * 1)  A patch which alters the behaviour of a program by forcibly overriding aspects of the original code at runtime.

Verb

 * 1)  To alter the behaviour of a program by forcibly overriding aspects of the original code at runtime.