Someone who goes hard at clubs and is willing to go after any milf he sees. A-Macs are very difficult to find. It is uncommon to find one. They like to sing and go hard at drinking.
The other day i was at the club and the A-Mac was living his life like there was no tomorrow.
Similar to the word amazing, but the letter 'c' gives it much more power and importance.
It is one of the best compliments out there, and should not be used lightly.