1. A best friend or good person. Used by males to other males, usually as a greet- ing or a term of endearment. In this sense the term probably spread from black American street gangs in the 1950s to working-class whites in the USA, Aus- tralia and, to a lesser extent, Britain.

Hey, ace!

2. Australian the anus. By association with arse and the black mark on a playing card.