metamorphosis

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A transformation, as by magic or sorcery.
• noun A marked change in appearance, character, condition, or function.
• noun 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.
• noun A usually degenerative change in the structure of a particular body tissue.

from The Century Dictionary.

• noun In music, either the same as variation (see variation, 9), or that extension or transformation of a theme or subject which often appears in modern music in the progress or development of an extended movement. From Beethoven onward the recognition of the essentially plastic nature of musical ideas (see idea, 9) has steadily advanced and constitutes one of the salient characteristics of recent composition.
• noun Change of form or structure; transmutation or transformation.
• noun A marked change in the form or function of a living body; a transformation resulting from development; specifically, in zoology, the course of alteration which an animal undergoes after its exclusion from the egg, and which modifies extensively the general form and life of the individual; particularly, in entomology, the transformations of a metabolous insect.
• noun In chem., that chemical action by which a given compound is caused, by the presence of a peculiar substance, to resolve itself into two or more compounds, as sugar, by the presence of yeast, into alcohol and carbonic acid.
• noun In botany, the various changes that are brought about in plant-organs, whereby they appear under changed or modified conditions, as when stamens are metamorphosed into petals, or stipules into leaves.

from the GNU version of the Collaborative International Dictionary of English.

• noun Change of form, or structure; transformation.
• noun (Biol.) A change in the form or function of a living organism, by a natural process of growth or development. Especially, that form of sexual reproduction in which an embryo undergoes a series of marked changes of external form, as the chrysalis stage, pupa stage, etc., in insects. In these intermediate stages sexual reproduction is usually impossible, but they ultimately pass into final and sexually developed forms, from the union of which organisms are produced which pass through the same cycle of changes. See Transformation.
• noun (Physiol.) The change of material of one kind into another through the agency of the living organism; metabolism.
• noun (Bot.) the doctrine that flowers are homologous with leaf buds, and that the floral organs are transformed leaves.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A transformation, such as that of magic or by sorcery
• noun A noticeable change in character, appearance, function or condition.
• noun 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.)
• noun pathology A change in the structure of a specific body tissue. Usually degenerative.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a complete change of physical form or substance especially as by magic or witchcraft
• noun the marked and rapid transformation of a larva into an adult that occurs in some animals
• noun a striking change in appearance or character or circumstances