Ace has many different meanings : - master - highest card - fast point for instance in tennis - allied air defence ground environment - Allied Command Europe - access control entry - Adverse Channel Enhancement - acetylcholinesterase - alcohol-chloroform-ether - adreno-cortical extract - angiotensin converting enzyme Slang : - to win (with sb) - cool! - to describe person as sb great - to manage well with a test

I know in slang many people call there friends thier ace. Since other than the joker the ace is the highest card in a deck its like calling them number one. For example. If someone asked if you are friends with someone. You can say yes thats my ace. P.S. : You may hear some people say aceboomcoon lol which is the same thing.