∙ Primarily, a square; hence, a square body of troops; a body of troops drawn up in a square. obsolete
∙ A body of cavalry comprising two companies or troops, and averaging from one hundred and twenty to two hundred soldiers. military, army
∙ A detachment of vessels employed on any particular service or station, under the command of the senior officer; as, the North Atlantic Squadron. military, navy
∙ A tactical air force unit; consists of at least two flights; multiple squadrons make up a group or wing (depending on particular air force). military, air force