c.1225, from O.Fr.
empereor (acc.), from L.
imperiatorem (nom.
imperiator) "commander, emperor," from stem of
imperare "to command" (see
empire). Originally a title conferred by vote of the Roman army on a successful general, later by the Senate on Julius and Augustus Caesar and adopted by their successors except Tiberius and Claudius. In the Middle Ages, applied to rulers of China, Japan, etc.; only non-historical European application in Eng. was of the Holy Roman Emperors (who in Ger. documents are called
kaiser), from 1297, until in 1804 Napoleon took the title "Emperor of the French."
Empress is attested from 1154; Queen Victoria in 1876 became "Empress of India."