Definition of keep someone after in English:

keep someone after

phrasal verb

US
  • Make a pupil stay at school after normal hours as a punishment.

    • ‘And, anyway, if a teacher was gonna keep him after, he'd rather it be Mr. Silurian than anyone else.’
    • ‘If you were in his last class of the day he'd keep the whole class after.’
    • ‘‘Where's Lily?’ she vaguely heard Christian ask. Natalie sighed. ‘Mrs. Wilcox kept her after.’’