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 late 13c., until in 1804 Napoleon took the title "Emperor of the French." Empress is attested from mid-12c.; Queen Victoria in 1876 became "Empress of India."