Dr. rer. nat.
Doctor rerum naturalium (Dr. rer. nat.), literally "Doctor of the things of nature", Doctor of Natural Sciences, is a post-graduate academic degree awarded by universities in Europe (e. g. Germany, Austria) to graduates in Mathematics, Physics, Chemistry, Biology, Geology, Computer Science or similar areas. These doctoral degrees are equivalent to a PhD.
In the Czech Republic (former Czechoslovakia), a similar designated degree, abbreviated RNDr., is awarded, but should not be confused with the Dr. rer. nat., as the RNDr. is only an extension of a master-like degree.