calm_down
1. [ verb ] become quiet or calm, esp. after a state of agitation
Synonyms: cool_off settle_down simmer_down chill_out cool_it calm
Examples:

"After the fight both men need to cool off." "It took a while after the baby was born for things to settle down again."

Related terms: change_state composure
2. [ verb ] make calm or still
Synonyms: calm quiet still tranquillise quieten tranquillize lull tranquilize
Examples:

"quiet the dragons of worry and fear"

Related terms: agitate comfort reassure pacify lull compose hush repose
3. [ verb ] become quiet or less intensive
Synonyms: lull
Examples:

"the fighting lulled for a moment"

Related terms: hush letup