majestic or magnificent:the bedroom is huge and very imperial
imperious or domineering:the party and its autocratic—many would say imperial—ways
2relating 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.
3chiefly historical (of a size of paper, in the UK) measuring 762 × 559 mm (30 × 22 inches).
a small pointed beard growing below the lower lip (associated with Napoleon III of France).
late Middle English: via Old French from Latin imperialis, from imperium 'command, authority, empire'; related to imperare 'to command'. Compare with emperor, empire, also with imperious
imperial in other Oxford dictionaries
Definition of imperial in the US English dictionary