Top definition
Latin for "not complete of mind", basically meaning "stupid". See: Ignoramus.
Bob: Hey, Mark...
Mark: What?
Bob: You're non compus mentus.
Mark: I don't know what that means, but fuck you anyway.
by Grammar_Nazi January 21, 2008
Get the mug
Get a Non Compus Mentus mug for your sister-in-law Helena.