noun, noun or participle which takes 'suru'
Refers to singing in a loud voice, often with enthusiasm or abandon. Can be used as a noun or with する to mean 'to sing loudly'.
彼は酒に酔って高歌した。
He sang loudly, drunk on sake.
カラオケで高歌するのが好きだ。
I like singing loudly at karaoke.