composition evolved shortly before 1600, by some enthusiastic Florentine amateurs who sought to bring back the Greek plays to the modern stage."
"No good opera plot can be sensible. ... People do not sing when they are feeling sensible." [W.H. Auden, 1961]
As a branch of dramatic art, it is attested from 1759. First record of opera glass "small binoculars for use at the theater" is from 1738. Soap opera is first recorded 1939, as a disparaging reference to daytime radio dramas sponsored by soap manufacturers.
opus1809, "a work, composition," esp. a musical one," from L. opus "a work, labor, exertion" (cf. It. opera, Fr. oeuvre, Sp. obra), from PIE base *op- (Gmc. *ob-) "to work, produce in abundance," originally of agriculture later extended to religious acts (cf. Skt. apas- "work, religious act;" Avestan hvapah-
"good deed;" O.H.G. uoben "to start work, to practice, to honor;" Ger. üben "to exercise, practice;" Du. oefenen, O.N. æfa, Dan. øve "to exercise, practice;" O.E. æfnan "to perform, work, do," afol "power"). The plural, seldom used, is opera.