hairsplitter
/ˈhɛrˌsplɪtər/
noun
- A person who makes very fine or overly subtle distinctions in arguments or reasoning, often to the point of being annoying or pedantic.
- My uncle is such a hairsplitter that he argued about the exact shade of blue in the sky for an hour.
- The debate turned frustrating when a hairsplitter interrupted to question the definition of 'freedom.'
- Don't be a hairsplitter in class; focus on the main idea instead of tiny details.