accession, accessory, accordance, addenda, addendum, additament, addition, additive, additory, additum, adjunct, adjuvant, agreement, alliance, alto, annex, annexation, appanage, appendage, appendant, appurtenance, appurtenant, association, attachment, augment, augmentation, baritone, bass, basso continuo, basso ostinato, bassus, cahoots, canto, cantus, cantus figuratus, cantus planus, co-working, coaction, coda, coetaneity, coetaneousness, coevalneity, coevalness, coexistence, coincidence, collaboration, collectivity, collusion, combination, combined effort, complement, concert, concerted action, concomitance, concomitant, concordance, concourse, concurrence, confluence, conjunction, consilience, conspiracy, contemporaneity, contemporaneousness, continuation, continuo, contralto, cooperation, corollary, correspondence, descant, drone, extension, extrapolation, figured bass, fixture, ground bass, increase, increment, isochronism, junction, line, offshoot, parasitism, part, pendant, plain chant, plain song, prick song, reinforcement, saprophytism, side effect, side issue, simultaneity, soprano, supplement, symbiosis, synchronism, synchronization, synergy, tailpiece, tenor, thorough bass, treble, undergirding, undersong, union, unison, united action, voice, voice part