One of my students asked me how the nickname Bill came from the full name William. Sadly, I could not give an answer. I would appreciate any help I could get.
Names, like other words, are sometimes subject to change over time. In one case, the Latin 'Ricardus' became the Anglo-Norman 'Ricard'. That, in turn, was shortened to 'Ric(k)' and then was playfully altered to the rhyming form that opens with the letter �d'. The Latin 'Guglielmus and French 'Guillaume' gradually became 'Bill' in much the same manner.