Synonyms/Hypernyms (Ordered by Estimated Frequency) of verb act_up

2 senses of act up

Sense 1
act up, carry on -- (misbehave badly; act in a silly or improper way; "The children acted up when they were not bored")
       => misbehave, misconduct, misdemean -- (behave badly; "The children misbehaved all morning")

Sense 2
act up -- (make itself felt as a recurring pain; "My arthritis is acting up again")
       => ache, smart, hurt -- (be the source of pain)