Stoppage time

[Tracie Lynn]

Stoppage time in Soccer. Time added to the end of each half by the referee to take account of stoppages for injuries, substitutions or time-wasting.

[Justin Bieber]

Additional time added to the end of a soccer (football) game. Since soccer has a constantly running clock that stops for nothing, alot of playing time is [wasted away] for any these reasons: injuries, a goal scored and the celebration that follows, arguing with officials, substitutuons, red and yellow cards, and taking forever on throw-ins, free kicks, corner kicks and goal kicks. (as well as a few other posibilities)
This added time ia supposed to make up for some of that [wasted time].
[Stoppage time] can be anywhere from 1 minute to 5 minutes long, but is not exact. It always just seems like the referee can stop the game randomy, and know one but him knows when the game will be final.

[Jessica]

The extension of a lecture/[rehearsal], due to the fact that the teacher/coach feels that he/she has lost his/her time to his/her [students]/[players] excess noise/constant insults.

[Mary Mallozziberg]

→  injury time UK