grammarian

noun

Etymology: Inherited from Middle English gramarien, from Middle French gramarien, gramairien. Displaced native Old English stæfcræftiga.

1. A person who studies grammar, either scientifically or (traditionally) unscientifically.

   “Huddleston and Pullum are well-known grammarians of the 21st century.”

   “The goal of a grammarian is to discover the morphemes and words within a language, and to discover how they combine in the grammar.”

2. A person who pedantically critiques the grammar of others' speech or writing, especially when unscientifically and misguidedly.

   “They spent hours disabusing the misinformed rants of various armchair grammarians.”