Taikun

Taikun (大君), spelled as tycoon during its brief usage in English language diplomatic notes in the 1860s, is an archaic Japanese term of respect derived from Chinese I Ching, which once referred to an independent ruler who did not have an imperial lineage.

The shōgun certainly could not call himself the Emperor of Japan (天皇, Tennō), but he also could not use the term "king" (国王, kokuō).

Still going back 1,000 years and more in history, Empress Kōgyoku (皇極天皇, Kōgyoku-tennō, 594–661) of Japan and predecessors are said to have had the title (大和大君), read "Yamato Taikun".

The word has entered the English language as tycoon,[3] where it has assumed the meaning of "a person of great wealth, influence or power".

Still, a "tycoon" is a person of great influence without formal title, whereas a "taikun" was a ruler without imperial lineage.

Tokugawa Yoshinobu , the last taikun
Letter of Abraham Lincoln to "Tycoon" Tokugawa Iemochi , announcing the departure of Townsend Harris . 14 November 1861.
Letter of Napoleon III to the Japanese "Taïcoun" nominating Léon Roches , in replacement of Duchesne de Bellecourt , 23 October 1863. Diplomatic Record Office of the Ministry of Foreign Affairs (Japan) .