Purist

['pjʊərɪst] or ['pjʊrɪst]

(noun.) someone who insists on great precision and correctness (especially in the use of words).

Edited by Ian--From WordNet

(n.) One who aims at excessive purity or nicety, esp. in the choice of language.

(n.) One who maintains that the New Testament was written in pure Greek.

Editor: Randolph