In Kafka's novel entitled Metamorphosis, a man wakes up to find he has turned into a cockroach. That kind of complete and startling change pretty much sums up the word.
When a caterpillar becomes a butterfly, it goes through a metamorphosis. An idea can undergo metamorphosis, or metamorphosize, too as can feelings. After you spend a full summer with your grandmother, your feelings about the woman may undergo a complete metamorphosis. While you were once afraid of the old woman, you now love her dearly.
n the marked and rapid transformation of a larva into an adult that occurs in some animals
hemimetabolism, hemimetaboly, hemimetamorphosis
incomplete or partial metamorphosis in insects
development of insects with incomplete metamorphosis in which no pupal stage precedes maturity
complete metamorphosis in insects