Short for William, or its Irish equivalent Uilliam, which nobody would ever be able to spell — a little more modern and youthful-sounding than William’s other nickname, Bill. It means strong-willed warrior, a trait that will become evident when he’s a toddler and you cut his banana wrong.
Liam itself is a nickname, and it’s kind of hard to shorten, unless you wanna go with Li. (Or Am — how existential.)
Famous people named Liam:
Actors Liam Hemsworth and Liam Neeson; singers Liam Gallagher and Liam Payne.
If you flip it around, it spells “mail.” So that’s … neat. Tori Spelling, Harrison Ford, and Rod Stewart must also think it’s neat, since they all have Liams.