act up Informal
Meaning: If a part of your body or a piece of equipment acts up, it doesn't work properly.Synonym: play up, malfunction
- act up My printer is acting up, so I'll have to get it fixed.
- act up I'll have to give the tennis a miss this week. My knee is acting up again.
act up: computer, printer, phone, air conditioner, knee, wrist, ankle, stomach
If your computer's acting up, it's