prescriptivist

noun

1. Someone who lays down rules regarding language usage, or who believes that traditional norms of language usage should be upheld.

   “The plutocratic tone and styptic wit of Safire and Newman and the best of the Prescriptivists is often modeled after the mandarin-Brit personas of Eric Partridge and H. W. Fowler, the same Twin Towers of scholarly Prescriptivism whom Garner talks about revering as a kid.”

adj

1. Having a tendency to prescribe.

   “In short, they tend to present Indian English as nothing more than "standard" English with a select collection of lexical peculiarities tacked on, as it were, many of which would be regarded as "errors" by prescriptivist language scholars.”