subsidiary /sʌbˈsɪ.di.əɹ.i/adjective 3noun 3forms 3 adjective3 •Auxiliary or supplemental.They constituted a useful subsidiary testimony of another state of existence. — 1823 •Secondary or subordinate. •Of or relating to a subsidy.George the Second relied on his subsidiary treaties. — 1836 noun3 •A company owned by a parent company or a holding company, also called daughter company or sister company. •One who aids or supplies; an assistant. •A subordinate theme. formssubsidiaries · more subsidiary · most subsidiary