2. Gambling term (most common in poker) descibing an angry or "reeling" state of mind usually caused by a big or unluck loss. People playing on tilt play below their usual abillity and usually make larger and more aggressive bets to try to quickly recover their loss. In poker, this is very valueble to other players at the table, hence worth keeping track of and/or attempting to cause. People known to be prone to tilting are often taunted or generally aggrivated when they take a loss and then egged on when they do tilt in order to keep them in this state as long as possible.
My stack was up to $250 but I lost $100 with a AA to a KQ and went on tilt. Before I knew it, it was all gone.