Regiment/ˈredʒɪmənt/ Definition 1 of 3Pro Tip 1/3Military Origin Originally refers to military units, can imply discipline and structure. The history of the regiment dates back to the 18th century. Pro Tip 2/3Group Size A regiment is larger than a company but smaller than a division in army hierarchy. She was promoted to command the entire regiment. Pro Tip 3/3Leadership Regiments are usually led by a Colonel, conveying a sense of authority. Colonel Smith took charge of the regiment last year.