Definify.com
Webster 1913 Edition
Metamorphic
1.
Subject to change; changeable; variable.
2.
Causing a change of structure.
3.
(Geol.)
Pertaining to, produced by, or exhibiting, certain changes which minerals or rocks may have undergone since their original deposition; – especially applied to the recrystallization which sedimentary rocks have undergone through the influence of heat and pressure, after which they are called metamorphic rocks.