The name reached its all-time peak in 1998 with 6 births ranking #2407. FALLING Recent data shows the name is currently falling.
Billy is the familiar short form of William and carries the inherited meaning usually given as "resolute protector". It feels open, friendly, and much less formal than the full traditional version.
Billy has long been used as both a nickname and a stand-alone given name. It remains especially familiar in Britain and the United States through its mix of informality and tradition.