word puritan
A closed-minded person who sees all language in black and white with no exceptions. They are sticklers for one dictionary as their lone authority on every word. They are anal sticklers about language and they refuse to accept any new slang words as legitimate additions to a certain language. Esp., English.
The Scrabble buff was a "word puritan" and he refused to accept any coinage of a new word that was not from his authoritative source.