Wiktionary
monkey patch
alt. (context programming neologism English) A patch which alters the behaviour of a program by forcefully override aspects of the original code at runtime. n. (context programming neologism English) A patch which alters the behaviour of a program by forcefully override aspects of the original code at runtime. vb. (context programming neologism English) To alter the behaviour of a program by forcefully override aspects of the original code at runtime.
Wikipedia
Monkey patch
A monkey patch is a way for a program to extend or modify supporting system software locally (affecting only the running instance of the program).