/jee ol"euh jee/ , n. , pl. geologies .
1. the science that deals with the dynamics and physical history of the earth, the rocks of which it is composed, and the physical, chemical, and biological changes that the earth has undergone or is undergoing.
2. the study of this science.
3. the geologic features and processes occurring in a given region on the earth or on a celestial body: the geology of Mars; the geology of eastern Kentucky.
[ 1680-90; GEO- + -LOGY ]