A Doctor of Philosophy (PhD or DPhil; Latin: philosophiae doctor or doctor in philosophia) is a terminal degree, that usually denotes the highest level of academic achievement in a given discipline and is awarded following a course of graduate study and original research. The name of the degree is most often abbreviated PhD (or, at times, as Ph.D. in North America), pronounced as three separate letters ( PEE-aych-DEE). The abbreviation DPhil, for "Doctor of Philosophy", is used by the University of Oxford.
https://en.wikipedia.org/wiki/Doctor_of_Philosophy