Refers to traditional popular songs, often from the Edo period or earlier, distinct from courtly or classical music.
There are many folk songs in this region that have been passed down since ancient times.
He is researching folk songs from the Edo period.
Compound of 俗 (ぞく, 'common, popular') and 曲 (きょく, 'song, tune'). The reading ぞっきょく is a regular sound change from ぞくきょく.