A multi-exposure photograph.
A chronophotograph shows overlapping pictures of something in motion. Usually the things it shows are happening rapidly, like a few seconds of a runner running or a bird flying. They can also be taken of slower things, like the sun moving across the sky, stars, or a plant growing. In these cases they may be taken over a period of months. They can add a new dimension to a photographic subject by allowing us to see how it changes over time.
Chronophotographs were invented by Etienne-Jules Marey.