What is "duke's coronet"

Duke \Duke\ (d[=u]k), n. [F. duc, fr. L. dux, ducis, leader, commander, fr. ducere to lead; akin to AS. te['o]n to draw; cf. AS. heretoga (here army) an army leader, general, G. herzog duke. See Tue, and cf. Doge, Duchess, Ducat, Duct, Adduce, Deduct.]

1. A leader; a chief; a prince. [Obs.]

   Hannibal, duke of Carthage.
   --Sir T. Elyot.

   All were dukes once, who were ``duces'' -- captains or leaders of their people.
   --Trench.

2. In England, one of the highest order of nobility after princes and princesses of the royal blood and the four archbishops of England and Ireland.

3. In some European countries, a sovereign prince, without the title of king.

4. pl. The fists; as, put up your dukes. [slang]

   Duke's coronet. See Illust. of Coronet.

   To dine with Duke Humphrey, to go without dinner. See under Dine.