look up any word, like dirty sanchez:
 
1.
A phrase which once meant "anything excluding" or "not" but now which means absolutely nothing and is used by Yankees to indicate a lack of intelligence unbeknown to them.
Paul (From Tennessee): I got an 11 on my ACT...

Brutus (From New York): I got a 35, I am all but intelligent.

Paul: Are you sure they didn't mix up our tests?

Brutus: Oh wait, I didn't even take the ACT.
by Rihanyce May 21, 2010
 
2.
Two people that aren't married, but are "all but" married. They have children, love each other, and live the typical lifestyle of a typical married couple.

Commonly, they will have both been married-divorced before, and have subsequently decided that marriage is almost completely unnecessary, outside of possible tax and health-care benefits.
I'd like you to meet my 'all buts', Crystal. We have one child together, and two by our previous marriages. As a 33 year old man with children I find it pretty lame (and childish) to refer to her has my girlfriend.
by MCOPE77 February 26, 2011