What is the X in X-mas?
"a drama sung" [Klein], 1640s, from Italian opera, literally "a work, labor, composition," from Latin opera "work, effort" (Latin plural regarded as feminine singular), secondary (abstract) noun from operari "to work," from opus (genitive operis) "a work" (see opus). Defined in "Elson's Music Dictionary" as, "a form of musical 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.
"a work, composition," especially a musical one, 1809, from Latin opus "a work, labor, exertion" (source of Italian opera, French oeuvre, Spanish obra), from PIE root *op- (Germanic *ob-) "to work, produce in abundance," originally of agriculture later extended to religious acts (cf. Sanskrit apas- "work, religious act;" Avestan hvapah- "good deed;" Old High German uoben "to start work, to practice, to honor;" German üben "to exercise, practice;" Dutch oefenen, Old Norse æfa, Danish øve "to exercise, practice;" Old English æfnan "to perform, work, do," afol "power"). The plural, seldom used as such, is opera.