1.  obbligato(n = noun.communication) obligato - a persistent but subordinate motif;
is a kind of motif, motive

2.  obbligato(n = noun.communication) obligato - a part of the score that must be performed without change or omission;
is a kind of section, subdivision

obbligato, n. (pl. -os) Mus. an accompaniment, usu. special and unusual in effect, forming an integral part of a composition (with violin obbligato).

Etymology:
It., = obligatory, f. L obligatus past part. (as OBLIGE)

N  accompaniment, adjunct, context, appendage, appurtenance, coexistence, concomitance, company, association, companionship, partnership, copartnership, coefficiency, concomitant, accessory, coefficient, companion, buddy, attendant, fellow, associate, friend, colleague, consort, spouse, mate, partner, co-partner, satellite, hanger on, fellow-traveller, shadow, escort, cortege, attribute, accompanying, concomitant, fellow, twin, joint, associated with, coupled with, accessory, attendant, obbligato, with, withal, together with, along with, in company with, hand in hand, side by side, cheek by jowl, cheek by jole, arm in arm, therewith, herewith, and, together, in a body, collectively, noscitur a sociis, virtutis fortuna comes.

N  music, concert, strain, tune, air, melody, aria, arietta, piece of music, work, number, opus, sonata, rondo, rondeau, pastorale, cavatina, roulade, fantasia, concerto, overture, symphony, variations, cadenza, cadence, fugue, canon, quodlibet, serenade, notturno, dithyramb, opera, operetta, oratorio, composition, movement, stave, passamezzo, toccata, Vorspiel, instrumental music, full score, minstrelsy, tweedledum and tweedledee, band, orchestra, concerted piece, potpourri, capriccio, vocal music, vocalism, chaunt, chant, psalm, psalmody, hymn, song, canticle, canzonet, cantata, bravura, lay, ballad, ditty, carol, pastoral, recitative, recitativo, solfeggio, Lydian measures, slow music, slow movement, adagio, minuet, siren strains, soft music, lullaby, dump, dirge, pibroch, martial music, march, dance music, waltz, solo, duet, duo, trio, quartet, quartett, septett, part song, descant, glee, madrigal, catch, round, chorus, chorale, antiphon, antiphony, accompaniment, second, bass, score, bourdon, drone, morceau, terzetto, composer, musician, musical, instrumental, vocal, choral, lyric, operatic, harmonious, Wagnerian, adagio, largo, larghetto, andante, andantino, alla capella, maestoso, moderato, allegro, allegretto, spiritoso, vivace, veloce, presto, prestissimo, con brio, capriccioso, scherzo, scherzando, legato, staccato, crescendo, diminuendo, rallentando, affettuoso, obbligato, pizzicato, desto, in notes by distance made more sweet, like the faint exquisite music of a dream, music arose with its voluptuous swell, music is the universal language of mankind, music's golden tongue, the speech of angels, will sing the savageness out of a bear, music hath charms to soothe the savage beast.