Bill \b(i)-ll\ as a boy's name is pronounced bil. It is of English origin. Nickname for William, used occasionally as an independent name. Before mid 19th century, Will was the more common nickname. Billie and Billy are pet forms, though Billie is frequently used for girls. Country-western singer Billy Ray Cyrus; singer Billy Joel; actors Bill Cosby, Billy Crystal, Bill Bixby, Billy Crudup, Billy Bob Thornton; designer Bill Blass.