That happened just once, though (as far as I know). "Natural philosophy" was a catch-all term for anything that involved the study of nature, before everything was formalized into categories such as physics and biology, and we decided "science" was a better, snappier term for it.

The word "scientist" was only invented in 1834. The scientist who coined it, William Whewell, also thought up "phycisist" and a whole bunch of other modern terms. [1] Interestingly enough, "naturalist" still survives as a legit term, as does "natural history".

[1] http://etymonline.com/index.php?allowed_in_frame=0&search=Wh...