To become still or calm.

To become calm or quiet.

intransitive. To become still or silent.

intransitive. Now chiefly North American. To become quiet; to quieten. Frequently with down.

Of persons: To become composed; to compose oneself to sleep; to come to a quiet or orderly state after excitement or restless activity. Also with down…

intransitive. To become smooth, calm, or tranquil.

intransitive. To become quiet (in various senses). Frequently with down.