Met`a*mor"phic (?), a. [See Metamorphosis.] 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.

• The process by which rocks are changed into other forms by the application of heat and/or pressure.
  
• A rock that has been changed from its original form by subjection to heat and/or pressure.