What does 'Monkey Patching' exactly Mean in Ruby?

Question

According to Wikipedia, a monkey patch is:

a way to extend or modify the runtime code of dynamic languages [...] without altering the original sou

Answer 1

Usually it is meant about ad-hoc changes, using Ruby open classes, frequently with low quality code.

Good follow-up on the subject:

http://www.infoq.com/articles/ruby-open-classes-monkeypatching