expression, godan verb (-u)
smile pleasantly; give a cheerful smile
Describes a brief, warm, and friendly smile, often with a sense of brightness or charm. The adverb にこっと adds a nuance of a sudden, gentle smile.
彼女は私を見てにこっと笑った。
She looked at me and smiled pleasantly.
赤ちゃんがにこっと笑うと、周りが明るくなる
When the baby gives a cheerful smile, the room brightens up.