Source : Webster's Revised Unabridged Dictionary (1913)

Primo \Pri"mo\, a. [It.] (Mus.)
   First; chief.

Source : WordNet®

primo
     adj : the best of its kind
     [also: {primi} (pl)]

primo
     n : the principal part of a duet (especially a piano duet)
     [also: {primi} (pl)]