Pronunciation: (fôr-mā'shun),[key] —n. 1. the act or process of forming or the state of being formed: the formation of ice. 2. the manner in which a thing is formed; disposition of parts; formal structure or arrangement.
3. Mil. a. a particular disposition of troops, as in columns, squares, etc.
b. any required assembling of the soldiers of a unit.
4. Geol. a. a body of rocks classed as a stratigraphic unit for geologic mapping. Cf. member (def. 8).
b. the process of depositing rock or mineral of a particular composition or origin.