na-adjective, adverb, adverb taking the 'to' particle, noun or participle which takes 'suru'
happy; euphoric; buoyant; walking on air
Colloquial mimetic word describing a light, cheerful, carefree mood. Often used in casual speech and writing, especially by younger speakers. Can be used adverbially with と or as a な-adjective.
彼女はルンルン気分で歌を口ずさんだ。
She hummed a song in a buoyant mood.
デートの前日、彼はルンルンしていた。
The day before the date, he was walking on air.