Billie \b(il)-lie\ as a girl's name (also used as boy's name Billie), is pronounced BILL-ee. It is of Old English origin. Originally a nickname for William. Now a feminine name, a short form for Wilhelmina (Old German) "will helmet, protection". Often combined with other names. Singer Billie Holliday; actress Billie Burke; tennis player Billie Jean King.
Billie has 10 variant forms: Billa, Bilee, Billi, Billie-Jean, Billie-Jo, Billie-Sue, Billina, Billy, Billye and Willa.
For more information, see also the related name Bobbie.