[met-uh-mawr-fiz-uh
m] 
| 1. | Geology. a change in the structure or constitution of a rock due to natural agencies, as pressure and heat, esp. when the rock becomes harder and more completely crystalline. |
| 2. | Archaic. metamorphosis. |
| met·a·mor·phism (mět'ə-môr'fĭz'əm) n. The process by which rocks are altered in composition, texture, or internal structure by extreme heat, pressure, and the introduction of new chemical substances. [metamorph(ic) + -ism.] |