1. A transformation, as by magic or sorcery.

2. A marked change in appearance, character, condition, or function.

3. Biology Change in the form and often habits of an animal during normal development after the embryonic stage. Metamorphosis includes, in insects, the transformation of a maggot into an adult fly and a caterpillar into a butterfly and, in amphibians, the changing of a tadpole into a frog.

4. A usually degenerative change in the structure of a particular body tissue.