Its source is wil helm, an Ancient Germanic name meaning "Determined protector."
This boy's name is used in Welsh.
When William the Conqueror led his army to victory at the Battle of Hastings in 1066, he not only captured England for himself and his barons, he captured it for a host of French names. Robert, Roger and Richard were numbered among the victors that day, but none were so triumphant as the name of the Conqueror himself.
William has remained a royal name in the United Kingdom for nearly one thousand years. If the current Prince William ascends the throne with that name, he will rule as William V.
Additionally, William figures prominently among nature's nobility, those who have achieved fame due to their skill. Poets Shakespeare, Blake and Wordsworth, three U.S. Presidents, novelists, scientists, and many star actors have added their personal luster to this royal name.