(music) A work of music or set of works with a specified rank in an ordering of a composer's complete published works. / A work, especially of art.

(Christianity) The Prelature of the Holy Cross and Opus Dei, a Roman Catholic organization composed of a prelate, secular clergy and lay people, whose mission is to spread the Catholic teaching that everyone is called to become a saint; its lay members, men and women, engage in the affairs of the world and seek to direct them "according to God's will".

A great or important work of literature, music or art, a masterpiece. / The best, most popular, or most renowned achievement of an author or artist, representing their major life effort.

The spiritual effect in the performance of a religious rite which accrues from the virtue inherent in it, or by grace imparted to it, irrespective of the performer.

(architecture, historical) An Ancient Roman construction technique, using irregular-shaped and randomly placed uncut stones or fist-sized tuff blocks inserted in a core of opus caementicium (Roman concrete).

Herringbone masonry.

Alternative form of magnum opus

The spiritual effect in the performance of a religious rite that is ascribed chiefly or exclusively to the disposition of the recipient.

plural of opuscule

An opuscule; a short work.