hold back

verb

1. To act with reserve; to contain one's full measure or power.

   “Don't hold back. Hit it as hard as you can.”

   “The TSSA union, which along with the RMT represents many of the staff affected by the closures, hasn't held back on its criticism.”

2. To contain; stop.

   “The dam can't hold back that much water.”

   “Fabregas coolly slotted home after Ben Parker held back Theo Walcott and only a super Kasper Schmeichel save stopped Denilson winning it for the Gunners.”

3. To delay the progress of, especially in school.

   “He's a year older than his classmates, because he was held back in second grade.”