noun a substance formed or deposited.
2. formation ·noun the arrangement of a body of troops, as in a square, column, ·etc.
3. formation ·noun the act of giving form or shape to anything; a forming; a shaping.
4. formation ·noun a group of beds of the same age or period; as, the eocene formation.
5. formation ·noun the manner in which a thing is formed; structure; construction; conformation; form; as, the peculiar formation of the heart.
6. formation ·noun mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations.