Formal:
* Linguist: This is a broad term for someone who studies language, including grammar. They may specialize in syntax, morphology, or other areas related to grammar.
* Grammatician: This is more specific and refers to someone who focuses on the study of grammar.
* Language specialist: This term encompasses various areas of language expertise, including grammar.
Informal:
* Grammar guru: This term suggests someone with a deep understanding and mastery of grammar.
* Grammar whiz: This implies someone who is particularly adept at grammar.
Other related titles:
* Editor: While not always focused solely on grammar, editors often have strong grammatical skills.
* Copyeditor: This is a specific type of editor who focuses on language and grammar.
* Proofreader: Proofreaders often check for grammar errors during the final stages of a publication.
The best term to use depends on the specific context and the person's area of expertise.