köken: Learnedly, from Hellenistic Koine Greek ναυαρχίς (nauarkhís, “of admiral's, commanding”) by ellipsis of Ancient Greek ναῦς f (naûs, “ship”), from the accusative singular τὴν (tḕn) ναυαρχίδα (nauarkhída).
Possibly coined in Japan as a compound of Middle Chinese-derived elements 旗 (ki, “flag”) + 艦 (kan, “warship, navy ship”), from the way that a fleet commander's signal flags would be flown from the mast of the flagship. Alternately, possibly from Middle Chinese compound 旗艦 (*ghiə *ɣam). Compare modern Chinese traditional 旗艦 /旗舰 (qíjiàn) and simplified 旗舰 (qíjiàn).