Source : WordNet®

terzetto
     n : the cardinal number that is the sum of one and one and one
         [syn: {three}, {3}, {III}, {trio}, {threesome}, {tierce},
          {leash}, {troika}, {triad}, {trine}, {trinity}, {ternary},
          {ternion}, {triplet}, {tercet}, {trey}, {deuce-ace}]
     [also: {terzetti} (pl)]

terzetti
     See {terzetto}