This idea, that originated with the Greeks, states that the universe is rational, orderly and governed by predictable laws. This contrasts with the idea of vitalism that states the universe is controlled by supernatural processes.
Religions are vitalistic and science is mechanistic.
A related set of ideas are causalism and teleology. According to teleology, the events in nature occur according to a predetermined plan or purpose. In contrast causalists deny that events have a predetermined plan. Rather, events occur in a stepwise fashion, each event setting the stage for the next. Science, obviously, operates from a causalistic perspective.