hair-splitter
nounUK /ˈheəˌsplɪtə/
US /ˈherˌsplɪtər/
A hair-splitter is a person who argues about very tiny details.
My uncle is a hair-splitter who argues about every little word in the rules.
RELATED WORDS
OTHER MEANINGS
2. A person who makes overly fine distinctions in an argument.
The hair-splitter insisted the difference between 'shall' and 'will' mattered.
3. Someone who focuses on small, unimportant differences instead of the main point.
Don't be a hair-splitter; the plan is good enough as it is.
4. A person known for finding tiny flaws in other people's work.
As a hair-splitter, she marked every comma error in the essay.