Become quiet or calm, especially after a state of agitation. Synonyms:calm, calm down, chill out, cool it, cool off, settle down."It took a while after the baby was born for things to settle down again."
... past baby days and resented baby treatment. The other teachers also had their hands full. Consequently the south wing was left entirely to Miss Stetson's supervision, and the south wing was a pretty sizable building and naturally under existing circumstances, it did not simmer down as promptly as under ordinary conditions. Miss Stetson was compelled to go from ... — A Dixie School Girl • Gabrielle E. Jackson