calm down
phrasal verb.to become quiet and relaxed after being angry, excited, or upset.
phrasal verb.to transition from a state of high emotional arousal or agitation to a state of composure; can be used intransitively or transitively.
“Please calm down and tell me what happened.”
“After the argument, he went for a long walk to calm down before speaking to her again.”
“The central bank's intervention was designed to calm down the volatile markets following the unexpected election results.”
often used as an imperative, though this can sometimes make an angry person feel more frustrated.
note the silent 'l' in 'calm'; as a transitive verb, the object can go between 'calm' and 'down' (e.g., 'calm him down').
while 'calm' is an adjective, the phrasal verb 'calm down' is required to describe the action of becoming peaceful.