O"pus (?), n.; pl. Opera (#). [L. See Opera.]
A work; specif. Mus., a musical composition.
Each composition, or set of pieces, as the composer may choose, is called an opus, and they are numbered in the order of their issue. (Often abbrev. to op.)
Opus incertum. [L.] Arch. See under Incertum.
© Webster 1913.