A comprimario is a supporting role in an opera. Derived from the Italian "con primario", or "with the primary", the term refers to a performer who sings small role pieces.
Many singers began their careers as comprimario singers; some have made a career out of singing such parts. Among these latter are singers such as Anthony Laciura, Jean Kraft, Nico Castel and Charles Anthony of the Metropolitan Opera.
References
Comprimario Wikipedia(Text) CC BY-SA