act

actnoun

An act is something that is done, a law made by a government, or a part of a play or show.

1. something donesomething that someone does

   countable [C]

   • It was a kind act to carry the old man's bags.
   • Helping a stranger is a simple act of kindness.
   • The rescue was seen as an act of great courage.
   • Breaking the window was a deliberate act, not an accident.

   Collocations

   adjective + noun a kind act, a brave act, a criminal act, a deliberate act

   noun + preposition an act of kindness, an act of violence, an act of courage

   Synonyms action

   Compare action (an act is one single thing done; action can mean the same, or the general process of doing something)

2. lawa law that has been formally passed by a government or parliament

   countable [C] often before another noun [before noun] government

   • Parliament passed a new act to protect the environment.
   • The act was signed into law last year.
   • Under this act, all workers get paid leave.

   Collocations

   verb + noun pass an act, amend an act, repeal an act

   adjective + noun a new act, a federal act

   Synonyms law

3. part of a playone of the main parts that a play or a show is divided into

   countable [C] theatre

   • The play has three acts.
   • The hero dies near the end of the second act.
   • There is a short break between acts.

   Collocations

   noun + noun act one, act two

   adjective + noun the final act

4. short performancea short performance that is one part of a show

   countable [C] theatre

   • The clown's act made everyone laugh.
   • She is the opening act for tonight's concert.
   • His juggling act was the best part of the circus.

   Collocations

   noun + noun a comedy act, the opening act, a circus act

See also law; play

actverb

To act is to do something, to do things in a certain way, to perform in a play or film, or to do someone else's job for a time.

1. do somethingdo something, especially to deal with a problem

   intransitive [I]

   • The government must act now to stop the flooding.
   • If we don't act quickly, it will be too late.
   • She acted at once and called for help.

   Collocations

   verb + adverb act quickly, act now, act immediately, act fast

   phrase a reason to act

2. behavedo things in a particular way

   intransitive [I] verb + adjective [V + adj]

   • Stop acting like a child.
   • He always acts tough in front of his friends. V + adj (informal, with an adjective)
   • She has been acting strangely all week.
   • They acted as if nothing had happened.

   Collocations

   verb + adverb act strangely, act responsibly, act selfishly

   phrase act like something, act as if

   Synonyms behave

3. performperform a part in a play, a film, or a show

   transitive or intransitive [T/I] verb + object [V + obj] verb + preposition + object [V + prep + obj] theatre

   • She has acted in films since she was a child. V + prep + obj
   • He acted the part of the king. V + obj
   • I've always wanted to act on stage.

   Collocations

   verb + preposition act in a film, act on stage, act in a play

   Synonyms perform

4. act asserve as, or do the same job as, someone or something else

   intransitive [I] verb + preposition + object [V + prep + obj]

   • The coach's office also acts as a meeting room. V + prep + obj
   • Sara agreed to act as translator for the visitors. V + prep + obj
   • Vitamin C acts as an antioxidant in the body. V + prep + obj

   Collocations

   verb + preposition act as something