Obbligato - Operetta
Oppure - OVPP
Obbligato - (Latin, Italian) "to oblige, fixed"; a musical passage or part which is pertinent to the composition; play as written; a part which must be included
Octatonic - any musical scale with eight notes; a series of eight notes to an octave in which tones and semitones alternate; Below: octonic scales
Octave - (Latin) "eight"; the interval between notes in which one tone is twice the pitch frequency of the other, or an octave apart; an eight note diatonic scale
Octave mark - notation directing musicians to play an octave higher (above) or lower (below) the written part; Right: Octave mark
Octet - (Latin) "eight of"; an ensemble of eight instruments or voices; a musical composition for eight instruments or voices
Octuple-whole-note - (Latin) "of eight"; note that is sustained for eight full bars
Octuple-whole-rest - (Latin) "of eight"; a rest which is sustained for eight bars
Ode - (Greek) "song"; an ancient Greek lyrical poem set to music; a ceremonial choral for honoring dignitaries at state occasions
Oeuvre - (French) "word"; a work of art or a complete body of artistic works
Ohne Dämpfer (German) "dampening"; without a mute; direction to refrain from using a mute to soften the tone
Oliphant - (French) "elephant"; medieval hunting horn made from elephant tusk
Ombra Scene - (French, Italian) "spirit, shade"; an operatic scene set in the 'underworld' which portrays the conjuring of spirits or demons
Open - a term directing instruments to play open pressing no valves or strings
Opera - (Italian) "labor, work"; a musical theatrical drama in which the actors are singers with the majority of acting parts sung as opposed to spoken as in a play
Opera Buffa - (Italian, French) "comic work, jest"; an 18th century popular Italian comic or satirical opera
Opéra Comique - (French) "comic opera"; a French operatic genre of 18th century with spoken dialogue and arias, originally incorporating vaudevilles, born of the Théâtre de l'Opéra-Comique in Paris during the mid 1700s
Opera Seria - (Italian) "serious opera"; a large 17th century opera of serious nature depicting historical or mythical content, opening with a three movement overture followed by a series of recitatives and arias, typically with thirty or more movements.
Operetta - (Italian) "little opera"; a light form of humorous opera with singing actors, dance, and spoken dialogue from the 16th century Italian genre of French vaudeville and English ballad opera; a critical and satirical 19th century Italian light operas
Oppure - (Italian) "or instead"; alternate method of performing indicated by notes or an additional staff; also ossia
Opus - (Latin) "work, work of art"; a method of identifying compositions by use of numbers by chronological order of production; abbreviated 'Op' for a single piece or 'Opp' for a series of works
Oratorio - (Italian) "to pray"; music composed in the 16th century for the 'Church of the Oratory of St. Philip Neri' in Rome; a large work involving a priest and sermon with choral hymnal, choir, and soloists, later with full orchestration
Orchestra - a large musical ensemble led by a conductor consisting of the families of musical instruments including brass, keyboard, percussion, strings, and woodwind consorts, often with vocal accompaniment; see also symphony
Ordinario - (Spanish) "normal"; 'naturale'; an instruction for bowed strings to discontinue a former command and return to playing the written part normally
Organ Trio - a Jazz or Rock music, an early 20th centur trio ensemble of an organ with two other instruments, typically electric guitar and drums
Organology - the science of musical instruments and their classification encompassing history, culture, and technical aspects of its sound production
Organum - Medieval plainsong of polyphonic melody
Ornament - notes added for embellishment of a melody
Ornamentation - (Latin) " decoration"; notes or other embellishments for decoration of the music to add emotion and style per the written symbol; one of the many notation symbols of musical embellishment; Right: see notations
Ossia - (Italian) "instead of"; use of an alternate method of performing a piece indicated by footnotes or an additional alternate staff; also oppure
Ottava - (Italian) "octav"; a prefix denoting an octave higher written above the staff or an octave lower when written below the staff
Ottava rima - (Italian) "rhyming octave"; a rhyming Italian stanza of eight eleven syllable lines, originating in the 13th century, used in the songs of Troubadours for religious verse and dramatic effects
Ottavino - (Italian) "little octave"; an alternative Italian term for the piccolo
Overblow - a means of producing a higher range of harmonics by increasing the air pressure at the mouthpiece
Overture - (Old French, Latin) "aperture"; an introduction into a more dramatic musical performance such as an opera or ballet, established in the 17th century, with a fast moving style progressing into a slower movement and returning to the fast (fast-slow-fast), then converted to the opposite of a slow-fast-slow style of intro about a century later
OVPP - abbreviation meaning "one voice per part"; the practice of using solo voices on each musical line or part in choral music
