calm downDad was really angry and it was a long time before he calmed down.
calmHe calmed the crying baby.
settle downChildren, settle down and take your seats!
simmer downOkay, simmer down - no one's trying to upset you.
cool down/offWhy don't you go for a walk and cool off?
chill outinformalMum, chill out! I'll be home before midnight, I promise!
placateThe company made many concessions in an attempt to placate the trade union.
mollifyHe issued an apology, but it's unclear whether that will mollify his critics.
sootheHe soothed the crying baby.
quieten (down)UKThe dogs will quieten down as soon as they get used to you.
quiet (down)USAll right, everyone, quiet down so we can begin the movie!