canto (n.)

1580s, "a section of a long poem," used in Italian by Dante, in English first by Spenser, from Italian canto "song," from Latin cantus "song, a singing; bird-song," from past participle stem of canere "to sing" (from PIE root *kan- "to sing").

In medieval music, canto fermo (1789, from Italian, from Latin cantus firmus "fixed song") was the ancient traditional vocal music of the Church, so called because set by authority and unalterable. After time other voices were added above and below it.