Deuce

The score that is first reached in any game when each player has won three points - in other words, the score is 40-40. For some arcane reason, it is not correct to call 30-30 "deuce," even though the game situation at that stage is exactly the same as it is at deuce. And when we say that deuce is reached "first" at 40-40, it is because it well may not be the only time in the game. One player or the other must win two points in succession after deuce in order to win the game, and if that doesn't happen, and the next two points are split, the score goes back to deuce and the combatants try, try again. It's never been known to go on forever, but it can go on quite a number of times.