metamorphosis

noun

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