Definition of: formation

(fôr·mā′shən) noun
1. The act or process of forming or of making by the combination of materials; also, the taking on of specific form; development.
2. Manner in which anything is shaped or composed.
3. The disposition of military troops as in column, line, or square.
4. Anything that is formed.
5. Geol. a Earthy or mineral deposits, or rock masses, named with reference to mode of origin. b A series of associated rocks, having similar conditions of origin.
6. Ecol. A fully developed plant association in a given area.