C2 [ C ] the way something is naturally made or the way it has been arranged:
a rock formation
cloud formations
C2 [ U ] the development of something into a particular thing or shape:
the formation of a crystal
in formation Activities that are done in formation are done in a pattern by a number of people, vehicles, etc. moving together:
marching in close formation
[ C ] an arrangement of a team's players on a football field:
There is a time for trying new formations and asking players to do slightly different things.
a 4-4-2 formation