Definition

1. Noun:

   • A thing done; a deed: An "act" is something that someone does, a specific action or behavior.
   • A law made by a government: An "act" is a formal written law passed by a legislative body like a parliament.
   • A main division of a play or opera: An "act" is one of the major sections into which a theatrical performance is divided.
   • A performance or routine: An "act" can be a short performance, often as part of a longer show (e.g., in a circus or variety show).
   • A display of pretense: An "act" can refer to behavior that is not genuine, intended to deceive or impress others.

2. Verb:

   • To perform a role in a play, film, etc.: To "act" means to portray a character in a dramatic performance.
   • To behave in a specified way: To "act" means to conduct oneself or behave.
   • To take action; to do something: To "act" means to perform a specific deed or take steps to achieve something.
   • To function or have an effect: To "act" means to operate or produce an effect in a particular way.
   • To pretend; to feign: To "act" means to behave in a way that is not sincere or genuine.

Examples of Usage

• Noun:

  • His generous act was appreciated by everyone. (The specific deed he did was generous.)
  • The government passed an act to protect the environment. (A formal law was passed.)
  • The first act of the play was very dramatic. (The first major section of the play.)
  • The magician's act was the highlight of the show. (The magician's performance.)
  • She's not really upset; it's just an act. (Her behavior is a pretense.)

• Verb:

  • She will act in a new movie next year. (She will perform a role.)
  • You need to act responsibly. (You need to behave responsibly.)
  • We must act quickly to solve this problem. (We must take action.)
  • The medicine takes time to act. (The medicine takes time to have an effect.)
  • He's acting surprised, but he already knew. (He is pretending to be surprised.)

Advanced Usage

• "to act on/upon something": to take action as a result of advice, information, or a feeling.
  • The police acted on a tip from the public. (The police took action based on the tip.)
• "to act as": to perform the function of; to serve as.
  • This substance acts as a catalyst. (This substance serves as a catalyst.)
  • She acted as manager while he was away. (She performed the manager's duties.)
• "to act for/on behalf of": to represent someone officially.
  • The lawyer acts for several major companies. (The lawyer represents them.)
• "to act up": (informal) to malfunction or behave badly.
  • My computer is acting up again. (My computer is malfunctioning.)
  • The children started acting up during the long car ride.* (The children started misbehaving.)

Variants and Related Words

• Action (n): The process of doing something; a thing done.
  • His quick action saved the day.
• Actor / Actress (n): A person whose profession is acting on stage, in films, or on television.
  • She is a famous actress.
• Active (adj): Engaging or ready to engage in physically energetic pursuits; in action.
  • He leads a very active lifestyle.
• Activity (n): A condition in which things are happening or being done.
  • There was a lot of activity in the market.
• Enact (v): To make (a bill or other proposal) law; to act out (a role or play).
  • Congress voted to enact the tax reform.

Synonyms

• Noun (deed): Deed, action, feat.
• Noun (law): Statute, law, bill.
• Verb (perform): Perform, portray, play.
• Verb (behave): Behave, conduct oneself.
• Verb (take action): Take steps, move, proceed.

Related Phrasal Verbs

• Act out: To express thoughts or feelings through actions, often unconsciously; to perform a story or scenario.
  • Children sometimes act out their frustrations.
  • The students acted out a scene from the novel.
• Act on/upon: (See "Advanced Usage" above).
• Act up: (See "Advanced Usage" above).
• Act for: (See "Advanced Usage" above).

Related Idioms

• A tough/hard act to follow: A performance or achievement that is so good it is difficult for the next person to equal it.
  • Her presentation was excellent; she's a tough act to follow.
• Get in on the act: To become involved in an activity that is already successful or popular.
  • Seeing the success of the new cafe, other businesses wanted to get in on the act.
• Read the riot act: To give someone a severe warning or reprimand.
  • The teacher read the riot act to the class about being late.
• Act of God: An event caused by natural forces beyond human control, such as a flood or earthquake.
  • The insurance policy does not cover damage caused by an act of God.
• In the act (of doing something): While doing something, especially something wrong.
  • The thief was caught in the act of stealing the car.

Noun

1. a manifestation of insincerity
   • he put on quite an act for her benefit
2. a short theatrical performance that is part of a longer program
   • he did his act three times every evening
   • she had a catchy little routine
   • it was one of the best numbers he ever did
3. a subdivision of a play or opera or ballet
4. something that people do or cause to happen
5. a legal document codifying the result of deliberations of a committee or society or legislative body

Verb

1. perform on a stage or theater
   • She acts in this play
   • He acted in `Julius Caesar'
   • I played in `A Christmas Carol'
2. behave unnaturally or affectedly
   • She's just acting
3. be engaged in an activity, often for no particular purpose other than pleasure
4. have an effect or outcome; often the one desired or expected
   • The voting process doesn't work as well as people thought
   • How does your idea work in practice?
   • This method doesn't work
   • The breaks of my new car act quickly
   • The medicine works only if you take it with a lot of water
5. be suitable for theatrical performance
   • This scene acts well
6. pretend to have certain qualities or state of mind
   • He acted the idiot
   • She plays deaf when the news are bad
7. discharge one's duties
   • She acts as the chair
   • In what capacity are you acting?
8. play a role or part
   • Gielgud played Hamlet
   • She wants to act Lady Macbeth, but she is too young for the role
   • She played the servant to her husband's master
9. behave in a certain manner; show a certain behavior; conduct or comport oneself
   • You should act like an adult
   • Don't behave like a fool
   • What makes her do this way?
   • The dog acts ferocious, but he is really afraid of people
10. perform an action, or work out or perform (an action)
    • think before you act
    • We must move quickly
    • The governor should act on the new energy bill
    • The nanny acted quickly by grabbing the toddler and covering him with a wet towel