The restatement, in close succession, of a melody (theme, motif) in different parts of a contrapuntal texture.  This device is most consistently employed in the canon, in which a whole voice-part is imitated in another.  Imitation of themes (subjects) is an essential feature of the fugue as well as the 16th-century motet and pre-fugal forms, the ricercar, canzona, fantasia, and capriccio.  While in a fugue the imitation is normally restricted to one theme, the earlier forms usually have a number of themes.

In the 14th century, imitation found its first systematic realization in the Italian caccia and French chace, which are extended two- and three-part canons.  Of greater importance to the development imitation are imitative passages found in a number of Italian madrigals and ballate of the 14th century.

The works of Obrecht, Isaac, and Josquin show more and more deliberate use of imitation, which around 1500 became an essential element of musical style.