Formation For*ma"tion (f[o^]r*m[=a]"sh[u^]n), n. [L. formatio: cf. F. formation.] 1. The act of giving form or shape to anything; a forming; a shaping. --Beattie. [1913 Webster]

2. The manner in which a thing is formed; structure; construction; conformation; form; as, the peculiar formation of the heart. [1913 Webster]

3. A substance formed or deposited. [1913 Webster]

4. (Geol.) (a) Mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations. (b) A group of beds of the same age or period; as, the Eocene formation. [1913 Webster]

5. (Mil.) The arrangement of a body of troops, as in a square, column, etc. --Farrow. [1913 Webster]

The Collaborative International Dictionary of English. 2000.