Billie

Billie is an English name that originated as a diminutive of William, itself derived from the Old High German elements wil (will, desire) and helm (helmet, protection), giving the combined sense of "resolute protector." It was initially used as a nickname for boys but became widely adopted as an independent feminine given name through the twentieth century. Notable bearers include jazz singer Billie Holiday, who helped cement the name's cultural prominence, and contemporary pop artist Billie Eilish. Related forms include Bill, Billy, and the source name William, with feminine cognates across other languages such as Wilhelmina and Guillemette.