- A transformation, such as that of magic or by sorcery
- A noticeable change in character, appearance, function or condition.
- (biology) A change in the form and often habits of an animal after the embryonic stage during normal development. (e.g. the transformation of a caterpillar into a butterfly or a tadpole into a frog.)
- (pathology) A change in the structure of a specific body tissue. Usually degenerative.