Grammar Nazis "Grammar Nazi" is a slang term for a person who is overly obsessed with language mechanics, and focuses upon mistakes made in grammar and spelling rather than the meaning/ content of what others write and say. This humorous video concerning an SS Officer (a Nazi) who is also a "Grammar Nazi" demonstrates many mistakes in English which are made commonly even by native speakers: http://www.youtube.com/watch?v=N4vf8N6GpdM