action · noun /ˈæk.ʃən/Full view
Nouns: act, action, actor, actress, inaction, interaction, reaction, transaction
Adjectives: acting
Verbs: act, interact, react
action (ACTIVITY)
B1 U things which are happening, especially exciting or important things
Dictionary examples:

I like movies with a lot of action. / I like action movies.

In her last novel, the action moves between Greece and southern Spain.

Learner example:

We’re plan[n]ing to see "King Arth[u]r." Everyone said it's a nice movie with some action and some mystery. (Preliminary English Test; B1; Arabic)

action (DO)
B2 C or U something that you do
Dictionary examples:

We must take action before the problem gets worse.

She has to accept the consequences of her actions.

What do you think is the best course of action?

Learner example:

I decided to take action on my own. (First Certificate in English; B2; Greek)

C1 C or U a process in a law court when a person claims to have been harmed
Dictionary example:

They are considering taking legal action against the company.

course of action
C1 something that you can do in a particular situation
Dictionary example:

I think the best course of action would be to write to him.

Learner example:

However, I believe that the best course of action in this case is to give our student a refund. (Certificate in Advanced English; C1; Greek)

action (FIGHTING)
C2 U fighting in a war
Dictionary example:

He was killed in action.

Learner example:

It was a shock when she got to know that her husband had been killed in action. (Certificate of Proficiency in English; C2; German)

action (PROCESS)
C2 no plural a movement or natural process
Dictionary example:

The rocks are smoothed by the action of water.

Learner example:

The area of Sayago - in the Spanish province of Zamora - and Tras-os-Montes, in Portugal, are joined by a natural border: the river Duero and the rocky canyon that has been eroded for millions of years by the action of the water. (Certificate of Proficiency in English; C2; Catalan)

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