Meaning & Origin
A diminutive of the male given name William.
Billy is a boy's and girl's baby name of Germanic origin, a diminutive of William, from the Old High German Willahelm, meaning "resolute protector" — combining wil (will) and helm (protection). Billy evolved from the older diminutive Will via the rhyming substitution common in medieval English.
Billy has been given as a formal first name throughout American history, particularly in the South and West. Billy the Kid is one of the most mythologized figures of the American frontier. Billy Joel, Billy Crystal, and Billy Idol show the name's enduring range across music, comedy, and rock. Friendly, confident, and entirely American.