im·pe·ri·al / imˈpi(ə)rēəl/ • adj. 1. of or relating to an empire: Britain's imperial era. ∎  of or relating to an emperor: the imperial family. ∎  majestic; magnificent: the bedroom is huge and imperial. ∎  imperious or domineering: the party and its autocratic—many would say imperial—ways.2. of, relating to, or denoting the system of nonmetric weights and measures (the ounce, pound, stone, inch, foot, yard, mile, acre, pint, gallon, etc.) formerly used for all measures in the UK, and still used for some.3. chiefly hist. (of a size of paper) measuring roughly 762 × 559 mm (30 × 22 inches).• n. a small pointed beard growing below the lower lip (associated with Napoleon III of France).DERIVATIVES: im·pe·ri·al·ly adv.

imperial of, relating to, or denoting the system of non-metric weights and measures (the ounce, pound, stone, inch, foot, yard, mile, acre, pint, gallon, etc.) formerly used for all measures in the UK, and still used for some. Also, (of a size of paper) measuring (in the UK) 762 × 559 mm (30 × 22 inches).

imperial XIV. — (O)F. impérial — L. imperiālis, f. imperium rule, EMPIRE; see -IAL.
Hence imperialism XIX;, imperialist XVII.