A referee that referee's a reserve game
The possessive form of the noun referee is referee's.
The 2nd referee assists the 1st referee.
the judges assist the referee.
a referee jersey
The plural of referee is referees.
An assist referee should know all about football. He should know as much as the referee so that if the referee is blinded or very far away the assistanat referee could give decession after consulting with the referee.
The umpire assists the referee.
"Arbitro" is referee in Spanish.