Noah Webster's New International Dictionary of the English Language

1. (n.) The act of giving form or shape to anything; a forming; a shaping.

2. (n.) The manner in which a thing is formed; structure; construction; conformation; form; as, the peculiar formation of the heart.

3. (n.) A substance formed or deposited.

4. (n.) Mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations.

5. (n.) A group of beds of the same age or period; as, the Eocene formation.

6. (n.) The arrangement of a body of troops, as in a square, column, etc.