king (n.) Look up king at Dictionary.com
Old English cyning "king, ruler," from Proto-Germanic *kuninggaz (cognates: Dutch koning, Old Norse konungr, Danish konge, Old Saxon and Old High German kuning, Middle High German künic, German König). Possibly related to Old English cynn "family, race" (see kin), making a king originally a "leader of the people;" or from a related root suggesting "noble birth," making a king originally "one who descended from noble birth." The sociological and ideological implications render this a topic of much debate.

Finnish kuningas "king," Old Church Slavonic kunegu "prince" (Russian knyaz, Bohemian knez), Lithuanian kunigas "clergyman" are loans from Germanic.
As leon is the king of bestes. [John Gower, "Confessio Amantis," 1390]
In Old English, used for names of chiefs of Anglian and Saxon tribes or clans, then of the states they founded. Also extended to British and Danish chiefs they fought. The chess piece so called from early 15c.; the playing card from 1560s; use in checkers/draughts first recorded 1820. Applied in nature to species deemed remarkably big or dominant (such as king crab, 1690s). In marketing, king-size is from 1939, originally of cigarettes.
[I]t was [Eugene] Field who haunted the declining years of Creston Clarke with his review of that actor's Lear. ... Said he, "Mr. Clarke played the King all the evening as though under constant fear that someone else was about to play the Ace." ["Theatre Magazine," January 1922]