metamorphosis

noun

1. A transformation, such as one performed by magic.
2. A noticeable change in character, appearance, function or condition.
3. 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.)
4. A change in the structure of a specific body tissue. Usually degenerative.