Definition: Away from Computer
(1)Can be used for online gaming in particular MMORPGS, when a player steps away from their PC.
(2) The act of leaving your PC unattended.
(3) Can be used in replacement of AFK, but more specific to leaving the the vicinity of the PC.
Cabal Online Player 1: I'm getting thirsty guys I'm going AFC.
Cabal Online Player 2: Yea good idea, I'm going AFC as well.
Matrix Online Player 1: Where did Melisa go?
Matrix Online Player 2: You mean Shadowfoxy? She went AFC...