Non Compus Mentus 

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.

Non Compus Mentus by Grammar_Nazi January 21, 2008

Non Compis Mentis

The oldest local sorority in the south, running forty years strong. The only local sorority on the Rollins College campus, it broke off from Pi Beta Phi in 1969, forming in 1970. Girls of NCM strive for individualism, leadership, and building resilience in young women. While often mocked for not being national, and, at the time of it's forming, breaking off from a national organization, the girls were said to be "out of their minds." Embracing this, the ladies of NCM named their sorority, "Non Compis Mentis" (modified), the Latin for "Not of Sound Mind."

The women of Non Compis Mentis are not your stereotypical sorority girls.

-"Hey John, did you see that sorority, Non Compis Mentis? They don't have a Greek name..."
-"Hells, yeah. Latin pwns."

Non Compis Mentis by Human Being #6498237192 February 7, 2010

non compos mentis 

Of latin origin literally meaning:
Not having control of ones mind, or being totally unique and the sort of person who makes you laugh

"Oh my god, he is suffering from non compos mentis but still kinda hot in an unstable way"

non compos mentis by Beefa August 3, 2007