1911 Encyclopædia Britannica/Canto
CANTO (from the Lat. cantus, a song), one of the divisions of a long poem, a convenient division when poetry was more usually sung by the minstrel to his own accompaniment than read. In music, the canto, in a concerted piece, is that part to which the air is given. In modern music this is nearly always the soprano. The old masters, however, more frequently allotted it to the tenor. Canto fermo, or cantus firmus, is that part of the melody which remains true to the original motive, while the other parts vary with the counterpoint; also in Church music the simple straightforward melody of the old chants as opposed to canto figurato, which is full of embellishments of a florid character (see Plain Song).