A musical setting of the five movements of the Ordinary of the Roman Catholic Mass that is unified by the presence of the entire texture of a pre-existing polyphonic work, represented by borrowed motifs and points of imitation. The relationship is usually clearest at the beginning, middle and end of each movement. The designation ‘imitation mass’, more in keeping with the terminology used in the 16th century to describe this type of composition, has been adopted by some scholars.
See also Borrowing in music; Mass, §II, 6–9; Parody (i).