Definition
To misbehave; to cause trouble.
To perform the duties of an appointment senior to that actually held; to deputise for a superior.
In Context
- "My allergies act up during hay fever season."
- "Children may act up in class in an effort to get attention."
- "My car started acting up after I drove through that huge puddle."
- "Acting up is always recommended when you find yourself under a new boss."
- "A few months through my contract, my clinical supervisor said that a registrar was leaving the post early for a research job, and asked if I’d be interested in acting up on the rota."