opus (n.)

"a work, composition," especially a musical one, 1809, from Latin opus "a work, labor, exertion" (source of Italian opera, French oeuvre, Spanish obra), from Proto-Italic *opes- "work," from PIE root *op- "to work, produce in abundance." The plural, seldom used as such, is opera. Opus Dei, literally "the work of God," is a Catholic organization founded in Spain in 1928 to re-establish Christian ideals in society through examples of the lives of the members.