Glossary

oblique motion

Two melodic lines where one moves while the other is stationary.

octave

The interval between the first and eighth degrees of the diatonic scale.

octet

A piece written for eight parts, or the group that performs such a piece.

oeuvre

(Fr.) opus.

Offertory

  1. A part of the Roman Catholic Mass (Proper), following the Credo and sung during the offering.
  2. In Protestant church services, any music sung or played during offering.

open fifth

A triad that does not contain a third.

opera

A dramatic work set to music in which all or most of the text is sung with instrumental accompaniment, costumes and sets.

opéra comique

Comic Opera.

operetta

A light opera.

opus

“Work.” With a number, used to show the order in which pieces were written or published.

oratorio

A musical setting for voices and orchestra of a text based on the Scriptures or an epic theme. Essentially, an opera without staging, scenery or costumes.

orchestration

The art of writing, arranging or scoring for the orchestra.

Ordinary

In the Mass, the parts that are used every day, as distinct from the Proper. The Ordinary consists of the Kyrie, Gloria, Credo, Sanctus, and Agnus Dei.

ornament

A melodic embellishment, either written or improvised. Types of ornaments included trills, turns, mordents, and grace notes.

overtone

A tone that is present in the sounding of a fundamental, due to the physics of the production of musical tones.

overture

The introductory music for an opera, ballet, or oratorio. A concert overture is an independent work.