A term for an offense that uses a variety of formations in order to confuse the defense. Most teams use a multiple offense to keep the defense from easily adjusting to a particular formation and being able to react quickly at the snap. Offenses can switch formations to keep the defense off balance or to put their players in better positions to make plays. Most teams will switch formations depending on whether they intend to run or pass on a given play.
Multiple offense is a rarely used term in modern football because very few teams today run their plays from a single formation. Most formation changes are made to put players in a position to be successful from the moment the snap is taken, or to place players in a position to make the defense make difficult adjustments before the snap. Formations will change based on the play call, particularly given the difference between running plays and passing plays.