Abbreviation for 'Armor Class'. In the latest edition of DnD, AC is a number which signifies the difficulty of hitting a target in combat; the higher the number, the harder it is.
It was impossible to hit that guy. His AC was /way/ too high.
By Grimrider
Allied Chat. Used in some online multiplayer games to instruct team-mates to turn on allied chat or to signify that you have turned on allied chat.
ac, ac on, turn on ac.
By K
n. abbreviation for Acura (type of car made by Honda)
That chick drives a pimp ass Acura Legend...dizaaaaam!
By dmplesUT
How to tell if you're a nerd: When hearing the letters AC you think of Asheron's Call.
buttsex
By yeah
Automatic Cositionada, which is fancy-fancy talk for 'let's get this party started, like instantly.'
Stan: I can't start my engine! Rex: You need to press the AC button.
By savvy_noir