'simmer down' definitions:

Definition of 'simmer down'

(from WordNet)
verb
Become quiet or calm, especially after a state of agitation; "After the fight both men need to cool off."; "It took a while after the baby was born for things to settle down again." [syn: calm, calm down, cool off, chill out, simmer down, settle down, cool it]

Synonyms of 'simmer down'

From: Moby Thesaurus

Words containing 'simmer down'