Metamorphic things have experienced some kind of transformation or change. A metamorphic rock, for example, started out as a different kind of rock and was transformed with heat or pressure.
Metamorphosis is a dramatic change, a transformation from one state to a completely different one. The adjective metamorphic describes something related to this kind of change. Every child should get the chance to watch the metamorphic process of a caterpillar becoming a butterfly. You might have a metamorphic summer, one in which you get your braces off and grow seven inches taller. In geology, metamorphic describes a specific process that some rocks undergo when heat and pressure changes them. The Greek metamorphoun, "to transform," is from meta, "change," and morphe, "form."