An onomatopoeic word for a light smooch or a small smacking sound (made by pursing the lips); often used with the verb 'suru' or with the particle 'と'.
彼女の頬にチュッとキスした。
He gave her a quick kiss on the cheek.
赤ちゃんがチュッと音を立てて唇を動かした。
The baby made a little 'chu' sound and moved its lips.
漫画ではキャラクターがチュッとキスをする場面がよく描かれる。
In manga, scenes where characters give a quick 'chu' kiss are often depicted.