Imitation
Imitation of a motif or theme in another voice.
What it means
Imitation denotes the imitation of a motif or theme in another voice, shortly after it has first sounded. The second voice takes over the same or a slightly altered shape, often at a different pitch level, while the first voice continues.
Musical use
Imitation is the most important constructive principle of many multi-voice forms: it forms the basis of the canon, in which all voices strictly imitate the same melody, and of the fugue, in which dux and comes imitate each other. In freer contrapuntal music too, for instance in Renaissance motets, imitative entries of different voices alternate and thus create coherence among them. The gap between entries can be large or, as in stretto, very small.
Imitation should be distinguished from the canon, a strict imitation sustained through the whole piece, whereas imitation in the general sense can also apply to just one section. It differs from mere repetition in that the imitation happens in another voice, usually offset in time.
Performance practice
When listening to an imitative movement, follow which voice presents the motif first and hear how the following voices take it up. When performing yourself, help the imitating entry stand out slightly in sound so that listeners can recognise the principle.