1An onomatopoeia for the sound or feeling of wind quietly entering through a gap, or for quiet, regular breathing/whistling; often written as 'すーすー'.
ドアの隙間から冷たい風がすうすう入ってくる。
Cold wind is slipping in through the gap in the door.
赤ちゃんはすうすうと寝息を立てている。
The baby is breathing quietly in their sleep.
窓を閉めると、部屋がすうすうして寒くなくなった。
When I closed the window, the room stopped feeling drafty.