The term 'pinball foul' is a term used in the game of pinball. It occurs when the player has made an illegal move, such as shaking the machine or using too much force on the flippers. The crossword solution for this term is 'TILT', which is the action that occurs when a pinball foul has been committed. When a player tilts the machine, the game ends and the player loses any points they had earned up to that point.