ˌWilliam of ˈOrange, King BrE AmE
(1650–1702) the king of Britain and Ireland from 1689 until his death, also called William III. He was married to the daughter of King James II, and was asked by James’s enemies to become king instead of him. William and his Protestant army beat James and his Catholic army at the Battle of the ↑ Boyne , and for this reason he is still greatly admired by Protestants in Northern Ireland who sometimes call him ‘King Billy’. William’s wife, Queen Mary II, had equal power, and people usually talk about the ↑ reign of William and Mary.