metamorphosis (n.)

1530s, "change of form or structure, action or process of changing in form," originally especially by witchcraft, from Latin metamorphosis, from Greek metamorphōsis "a transforming, a transformation," from metamorphoun "to transform, to be transfigured," from meta, here indicating "change" (see meta-) + morphē "shape, form," a word of uncertain etymology.

The biological sense of "extensive transformations an animal (especially an insect) undergoes after it leaves the egg" is from 1660s. As the title of Ovid's work, late 14c., Metamorphoseos, from Latin Metamorphoses (plural).