: change of physical form, structure, or substance
: a marked and more or less abrupt developmental change in the form or structure of an animal (as a butterfly or a frog) occurring subsequent to birth or hatching
In biology, any striking developmental change of an animal's form or structure, accompanied by physiological, biochemical, and behavioral changes. The best-known examples occur among insects, which may exhibit complete or incomplete metamorphosis (seenymph). The complete metamorphosis of butterflies, moths, and some other insects involves four stages: egg, larva (caterpillar), pupa (chrysalis or cocoon), and adult. The change from tadpole to frog is an example of metamorphosis among amphibians; some echinoderms, crustaceans, mollusks, and tunicates also undergo metamorphosis.