What does "secondo" describe in a duet?

In the context of a duet, the term "secondo" refers to the second part or voice within the musical arrangement. In many musical compositions, particularly in vocal or instrumental duets, the "secondo" part typically complements the "primo" part, which is often the main melody or lead line. The "secondo" can provide harmony, counter-melody, or supporting lines that enrich the overall texture of the music.

This terminology is derived from Italian musical language, where "primo" means first and "secondo" means second. Understanding this distinction is crucial in analyzing and performing duets, as the relationship between the two parts contributes significantly to the piece's emotional expression and musical dialogue. Thus, recognizing "secondo" as the second part is essential for both performers and listeners in appreciating the full structure and interaction within a duet.