act

1 noun (C)

1 ACTION (C) a particular kind of action: a criminal act | act of kindness/revenge/courage etc: The Bishop condemned the attack as an act of mindless violence. | a supreme act of heroism | the sexual act (=the act of having sex)

2 be in the act of doing sth to be doing something at a particular moment, especially something that you should not do: catch sb in the act (of doing sth): The photo shows her in the act of raising her gun to fire. | The thief was caught in the act.

3 LAW (C) a law that has been officially accepted by Parliament or Congress: the 1991 Prevention of Terrorism Act | an act of Congress

4 PRETENDING (singular) insincere behaviour in which you pretend to have a particular kind of feeling: A lot of people think Betty's very kind and caring, but it's all just a big act. | put on an act (=pretend to have a particular feeling): He isn't really ill - he's just putting on an act.

5 get your act together informal to do something in a more organized way or use your abilities more effectively: She could be an excellent photographer, if only she got her act together a bit more.

6 get in on the act informal to take part in an activity that someone else has started, especially in order to get a share of the advantages for yourself.

7 PLAY (C) one of the main parts into which a stage play, opera etc is divided: Hamlet eventually kills the king in Act 5. | Everything is resolved in the final act.

8 PERFORMANCE (C) one of the several short performances in a theatre or circus (1) show: They used to do a comedy act together.

9 PERFORMER (C) a performer, singer, group of musicians etc: top-selling British act `The Happy Mondays'

10 act of God an event that is caused by natural forces, such as a storm, flood, or fire, which you cannot prevent or control

11 act of worship an occasion when people pray together and show their respect for God

12 balancing/juggling act the action of doing several different kinds of work at the same time

-see also: clean up your act clean 2 2 verb

1 DO SOMETHING

a) (I) to do something to deal with an urgent problem, especially by using your official power or authority: The UN Security Council must act to end the war in Bosnia.

b) (intransitive always + adv/prep) to do something in a particular way or for a particular reason: The killer claims he was acting in self-defence. | I acted more out of compassion than anything else. | act in good faith (=do something honestly without intending to deceive anyone): The shop manager says they acted in good faith and that they didn't know the camera was damaged. | act on (sb's) advice/orders/suggestion etc (=do what someone has advised, ordered etc): Acting on a friend's advice, he bought $50,000 of shares in a television company. | act on information (=do something because of information you have received): The police were acting on information from a member of the public.

2 BEHAVE (intransitive always + adv/prep) to behave in a particular way: act strangely/stupidly/correctly etc: Henry's been acting very strangely recently. | The teacher acted perfectly correctly under the circumstances. | act like/act as if: If you act like a child, you're going to be treated like a child. | He acted as if he'd never seen me before. | act your age spoken (=used to tell someone to be sensible and stop behaving like a child) | act the fool (=behave in a stupid and annoying way): Stop acting the fool, will you!

3 HAVE AN EFFECT

a) to have a particular effect or use

(+ as): The sugar in the fruit acts as a preservative. (+ on): Antibiotics act on the bacteria that cause the disease.

b) to start to have an effect: It takes a couple of minutes for the drug to act.

4 PRETEND (I, T) to pretend to have particular feelings, qualities etc: act innocent/stupid/hurt etc: She suddenly started acting all upset so that the others would feel sorry for her. | act the fool/hero etc: Whenever they're in public he always acts the loving husband. | act as if/act like: They were all trying to act as if nothing had happened.

5 PLAY/FILM ETC (I, T) to perform in a play or film: I first started acting when I was 12 years old. | act a part/role etc: Who acted the part of Miss Ceeley? | well/badly acted (=performed well or badly): I thought the play was extremely well acted.

6 LAWYER ETC act for sb/act on sb's behalf to represent someone, especially in a court of law or by doing business for them: I'm acting on behalf of my client, Mr Harding.

7 DO THE JOB OF act as to do a particular job for a short time, for example while the usual person is absent: Mrs Odell is on holiday, and I'm acting as her replacement till she gets back. | My brother speaks French - he will act as interpreter.

-see also: acting 1 act sth out phrasal verb (T)

1 if a group of people act out an event, they show how it happened by pretending to be the people who were involved in it

2 to express your feelings about something through your behaviour or actions, especially when you have been feeling angry or nervous: Teenagers can act out their anxieties in various aggressive ways.

act up phrasal verb (I) informal

1 if children act up, they behave badly

2 if a machine or part of your body acts up, it does not work properly: The photocopier has started acting up again.