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.

Definitions of metamorphosis

n a striking change in appearance or character or circumstances

“the metamorphosis of the old house into something new and exciting”
Type of:
alteration, revision
the act of revising or altering (involving reconsideration and modification)

n a complete change of physical form or substance especially as by magic or witchcraft

Type of:
transformation, translation
the act of changing in form or shape or appearance

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
heterometabolism, heterometaboly
development of insects with incomplete metamorphosis in which no pupal stage precedes maturity
holometabolism, holometaboly
complete metamorphosis in insects
Type of:
biological process, organic process
a process occurring in living organisms