Emily Dickinson Lexicon

FOR-MA'TION, n. [Fr. from L. formatio.]

1. The act of forming or making; the act of creating or causing to exist; or more generally, the operation of composing, by bringing materials together, or of shaping and giving form; as, the formation of the earth; the formation of a state or constitution.
2. Generation; production; as, the formation of ideas.
3. The manner in which a thing is formed. Examine the peculiar formation of the heart.
4. In grammar, the act or manner of forming one word from another, as controller from control.
5. In geology, formation may signify a single mass of one kind of rock, more or less extensive, or a collection of mineral substances, formed by the same agent, under the same or similar circumstances; or it may convey the idea, that certain masses or collections of minerals were formed not only by the same agent, but also during the same geological epoch. In this latter sense the term is almost always employed. Cleaveland. Formation is that collection or assemblage of beds or layers, strata or portions of earth or minerals, which seem to have been formed at the same epoch, and to have the same general characters of composition and lodgment. Dict. Nat. Hist.