Is a stage of a butterfly Metamorphic?

Answer 1

metamorphic is a geological term used for structural change in rocks.

I believe the word you are looking for is metamorphosis, which is an rapid change in animal's morphology (shape). Butterflies undergo this process in transforming from a caterpillar to what we generally recognise as a butterfly.

Answer 2

You must be referring to the Metamorphosis stage of the butterfly called the Pupa Stage. It is also referred to sometimes as the Chrysalis Stage. It is a resting stage in which the cells undergo dramatic rearrangement and changes. The Adult form that emerges looks nothing like the nymph (Caterpillar) stage of the butterfly