act, /ækt/, acted, acted, acting
Act for sb: if someone, especially a lawyer acts for you, you employ them to deal with something for you or to speak for you in a court of law:
Lawyers, acting for ex-smokers are suing the big tobacco companies for billions of dollars.
The buyer of the painting said he was acting for an American client wished to remain anonymous.
Similar to: represent
Act on/upon
Act upon is more formal than act on and is mostly used in writing.
Act on/upon to do what someone has advised/ordered you to do, or do something because you have received some information or had an idea:
Acting on a hunch, she went into his study and looked through his letters.
Act on sb’s suggestion/orders/advice:
I realize now that I should have acted on my father’s advice.
Act on information: Police say they were acting on information from an undisclosed source.
Act out
Act out sth, act sth out
1 To perform the events in a story, play or situation:
We had to act out the story of Jesus’ birth in Bethlehem.
Like every teenager, Kylie acted out her fantasies of pop stardom in front of her bedroom mirror.
2 To express your feelings and emotions through your behaviour, especially as a way of getting rid of your feelings of unhappiness and anger:
Teenagers often act out their frustrations by turning against their parents.
Similar to: vent
Act up
1 To behave badly – used especially about children:
He was always acting up in class caused his teachers no end of trouble.
Similar to: play up BrE informal.
2 informal if a machine or a part of your body acts up, it starts to hurt or stops working properly:
My elbow started acting up again and I had to stop playing.
My car is acting up again.
