The term "army group" refers to a military organization that is made up of multiple armies. Some synonyms for "army group" include "corps d'armee," "task force," and "battle group." Another common term used to describe a large military organization is "field army," which is typically composed of multiple corps, divisions, and brigades. In addition, the terms "force," "command," and "unit" can also be used to refer to an army group. Overall, these synonyms all describe a large-scale military organization that is tasked with carrying out complex missions and operations on the battlefield.