geology

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The scientific study of the origin, history, and structure of the earth.
2. n. The structure of a specific region of the earth's crust.
3. n. A book on geology.
4. n. The scientific study of the origin, history, and structure of the solid matter of a celestial body.

Century Dictionary and Cyclopedia

1. n. The science of the past and present condition of the earth, with special reference to the physical changes which it has undergone or which may still be taking place. Almost every branch of physical and natural science is, or may be, called upon to throw light on the problems which present themselves to the geologist. Closely connected with geology, and indeed almost inseparable from it, is paleontology, or the study of ancient forms of life, since the rocks are found on examination to contain in many places remains of plants or animals, sometimes closely resembling, and often very different from, any now living on the earth. It is almost exclusively the order of succession of forms of life thus found which gives the geologist the means of making out a chronological arrangement for the different stratified formations. Physical geography, or physiography, is the necessary introduction to geology, and forms the link which unites the work of the geographer to that of the geologist. Abbreviated geology See paleontology, petrography, and lithology.
2. n. . It is usually subdivided into Geognosy, or the description of the materials of the earth (sometimes called lithologic or petrographic geology)
3. n. The geological conditions or features of a place: as, the geology of a district.

Wiktionary

1. n. The science that studies the structure of the earth (or other planets), together with its origin and development, especially by examination of its rocks

GNU Webster's 1913

1. n. The science which treats: (a) Of the structure and mineral constitution of the globe; structural geology. (b) Of its history as regards rocks, minerals, rivers, valleys, mountains, climates, life, etc.; historical geology. (c) Of the causes and methods by which its structure, features, changes, and conditions have been produced; dynamical geology. See Chart of The Geological Series.
2. n. A treatise on the science.

WordNet 3.0

1. n. a science that deals with the history of the earth as recorded in rocks