Liam is the Irish short form of William, which goes back to the Germanic Willahelm and means "resolute protector" or "strong-willed warrior". For a long time it was mostly used in Ireland, where it became a given name in its own right. In the United States Liam climbed from number 140 in 2000 into the top 10 by 2012 and has been the most popular boys' name every year since 2017.