formationn.[L. formatio: cf. F. formation.]1. The act of giving form or shape to anything; a forming; a shaping.(Beattie.)2. The manner in which a thing is formed; structure; construction; conformation; form; as, the peculiar formation of the heart.()3. A substance formed or deposited.()4. (Geol.) Mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations.()5. (Mil.) The arrangement of a body of troops, as in a square, column, etc.(Farrow.)