calm³ (also calm down) verb [intransitive and transitive]
[Word Family: noun: calm, calmness; verb: calm; adverb: calmly; adjective: calm]

1. to become quiet and relaxed after you have been angry, excited, nervous, or upset, or to make someone become quiet and relaxed:
He tried to calm the frightened children.
Calm down and tell me what happened.
We tried to calm people’s fears.
calm yourself (down)
She lit a cigarette to calm herself down.

2. if a situation calms down, it becomes easier to deal with because there are fewer problems and it is not as busy as it was before:
It took months for things to calm down after we had the baby.

[TahlilGaran] Dictionary of Contemporary English ▲

calm down
to relax
The woman finally calmed down after the accident.

[TahlilGaran] English Idioms Dictionary ▲

calm down
v. phr. To become quiet; relax.
"Calm down, Mr. Smith," the doctor said with a reassuring smile. "You are going to live a long time."

[TahlilGaran] English Idioms Dictionary ▲