The Collaborative International Dictionary of English v.0.48:
Obligato \Ob"li*ga"to\, a. [It.] See Obbligato. [1913 Webster]WordNet (r) 3.0 (2006):
obligato n 1: a persistent but subordinate motif [syn: obbligato, obligato] 2: a part of the score that must be performed without change or omission [syn: obbligato, obligato]