An Encylopedia Britannica Company

act

1 act /ˈækt/ noun
plural acts
1 act
/ˈækt/
noun
plural acts
Britannica Dictionary definition of ACT
[count] : something that is done
see also sex act
◊ An act of God is a natural event (such as a storm or earthquake) that cannot be controlled by people.
[count] : a law made by a group of legislators
[count] : one of the main divisions of a play or opera
[count]
: one of the performances in a show
: a show that a person or group performs often
: a person or group that performs in shows
◊ A balancing act or juggling act is an attempt to do several different things or deal with several different situations at the same time.
see also class act, a hard/tough act to follow at follow
[singular] : a way of behaving that is not honest or sincere

clean up your act

see clean up at 2clean

get into the act

or get in on the act
: to start to participate in an activity

get your act together

see get together at get

in the act (of doing something)

: while doing something
2 act /ˈækt/ verb
acts; acted; acting
2 act
/ˈækt/
verb
acts; acted; acting
Britannica Dictionary definition of ACT
[no object] : to do something : to take action
[no object] : to behave in a particular way
◊ To act the part is to behave the way that people in a particular role usually behave.
◊ To act your age is to behave the way that people your age should behave and not to behave like a younger person.
◊ To act like a particular kind of person or thing is to behave the way that person or thing behaves.
see also 2act 3c (below)
[no object] : to behave in a way that is not sincere or honest
[linking verb] : to pretend to be something
[no object] : to pretend that something is true usually used in the phrases act as if, act as though, and (chiefly US) act like
see also act like at 2act 2 (above)
: to perform the words and actions of a character in a play, movie, etc. : to perform as an actor
[no object]
[+ object]
[no object] : to do the work of a particular kind of person or thing : to perform a certain function or role + as
[no object] : to make something happen : to have a particular effect
often + on see also act on/upon (below)

act on/upon

[phrasal verb]
act on/upon (something)
: to use (something, such as a feeling or suggestion) as a reason or basis for doing something
see also 2act 6 (above)

act out

[phrasal verb]
: to behave badly especially because you are feeling painful emotions (such as fear or anger)
act out (something) or act (something) out : to show that you are feeling (a painful emotion) by acting in ways that are not good or acceptable
act out (something) or act (something) out
: to perform (a play, a character in a movie, etc.)
: to do and say the things that happen in (a movie, past event, etc.)

act the fool

see 1fool

act up

[phrasal verb]
: to behave badly : to act in a way that is not polite or acceptable
of a machine : to not work properly
of a disease : to become worse and to start causing pain or physical problems