Meaning of ACT UP in English

ACT UP

1.

If something is acting up, it is not working properly. (INFORMAL)

She was messing with the coffee pot, which was acting up again.

= play up

PHRASAL VERB: usu cont, V P

2.

If a child is acting up, they are behaving badly. (INFORMAL)

= play up

PHRASAL VERB: usu cont

Collins COBUILD.      Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) .