Definition of "Formation" :
noun: the act of forming or establishing something
noun: the act of fabricating something in a particular shape
noun: creation by mental activity
"The formation of sentences."
noun: a particular spatial arrangement
noun: an arrangement of people or things acting as a unit
"A defensive formation."
noun: (geology) the geological features of the earth
noun: natural process that causes something to form
"The formation of gas in the intestine."