sumpsimus
/ˈsʌmpsɪməs/
noun
- A person who insists on using a correct but less common word or expression instead of a more common but technically incorrect one.
- My teacher is a real sumpsimus; she always corrects anyone who says 'between you and I' instead of 'between you and me.'
- Being a sumpsimus can make you unpopular at parties if you keep correcting people's grammar.
- He's such a sumpsimus that he refuses to say 'ATM machine' because the 'M' already stands for 'machine.'