1857, title given by foreigners to the shogun of Japan (said to have been used by his supporters when addressing foreigners, as an attempt to convey that the shogun was more important than the emperor), from Jap. taikun "great lord or prince," from Chinese tai "great" + kiun "lord." Transf. meaning "important person" is attested from 1861, in ref. to U.S. president Abraham Lincoln (in Hay's diary); specific application to "businessman" is post-World War I.