throw in

Short definition from Wiktionary

Noun

1. 1
   Alternative form of throw-in.
2. 2
   A set-piece where the ball is thrown back into play
3. 3
   A throw of the ball back into play by the boundary umpire. The umpire faces away from the players and throws it in over his or her shoulder (so as to clearly not favour either side by where exactly it's thrown).
4. 4
   the start time of a Gaelic football match, comparable to kick off in other games.
5. 5
   An extra item added free of charge; a product that is thrown in with another.

Verb

1. 1
   Used other than figuratively or idiomatically: see throw, in.
2. 2
   To add something extra free of charge.
3. 3
   To include in a calculation.
4. 4
   To quit, to fold.
5. 5
   To inject, as a fluid.