- quieten⇄quieten,
(Especially British.) - quieten⇄v.i. to become quiet.
Ex. Her heart had quietened down while she rested (Joseph Conrad). The situation will somehow quieten down one day, and the old order will be able to survive (London Times). - quieten⇄v.t. to make quiet.
Ex. At last ... to quieten them, I promised to ... write a short story (Arnold Bennett).