The verb has 3 meanings:
Meaning #1:
become quiet or calm, esp. after a state of agitation
Synonyms: calm, cool off, chill out, simmer down, settle down, cool it
Meaning #2:
make calm or still
Synonyms: calm, quiet, tranquilize, tranquillize, tranquillise, quieten, lull, still
Meaning #3:
become quiet or less intensive
Synonym: lull





