Metamorphic rocks, one of the three rocks that make up the Rock Cycle. The others are sedimentary and igneous rocks. Metamorphic means to morph into something else…like a caterpillar turning into a butterfly is called metamorphosis. It comes from the Greek word morph to form. In the rock cycle, any of the three rocks can turn into the others. A metamorphic rock is either a sedimentary or igneous rock that has transformed or metamorphosed into a new kind of rock.