(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.

Herringbone masonry.

(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).

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.

An opuscule; a short work.

A small or petty work.