battalion UK /bəˈtæl.i.ən/US /bəˈtæl.jən/noun 4verb 1forms 3 noun4 •An army unit having two or more companies, etc. and a headquarters. Traditionally forming part of a regiment. •(US) an army unit having two or more companies, etc. and a headquarters; forming part of a brigade. •Any large body of troops. •A great number of things. verb1 •To form into battalions. formsbattalioned · battalioning · battalions