Origin: 1325–75; Middle English < Late Latin imperiālis, equivalent to Latin imperi(um) imperium + -ālis-al1; replacing Middle English emperial < Middle French < Late Latin, as above
late 14c., "having a commanding quality," from O.Fr. imperial (12c.), from L. imperialis "of the empire or emperor," from imperium (see empire). Meaning "of or pertaining to an empire" (especially the Roman) is from late 14c.