It is either ad in or ad out. If the server won the point it is ad in and if the returner won the point then it is ad out.
Deuce
The word comes from the French phrase deux, which means "at two" (as in needing two more points to win). Also, there is a Latin prefix in it (du) which mean two; twice.
égalité is a French word, and 'deuce' isn't.
The typical sport that uses the term, "deuce", is Tennis or Table Tennis.
In tennis, when both opponents are tied at 40-40, the score is called deuce. Deuce changes to advantage when one opponent scores after achieving deuce.
Deuce is where both players are on 40 in a match of tennis
tennis
The term is called "Deuce."
40:40 Deuce in Tennis
4040 is deuce in tennis
40-40
Deuce.