资料来源 : Webster's Revised Unabridged Dictionary (1913)

Secondo \Se*con"do\ (?; It.), n. [It.] (Mus.)
   The second part in a concerted piece.

资料来源 : WordNet®

secondo
     n : the second or lower part of a duet (especially a piano duet)
     [also: {secondi} (pl)]