The name was probably taken from the sign of a lamb at an inn, the young of the sheep kind; Welsh, Llamer, to skip; Gaelic, Leum. The primitive Celtic or Gaelic Lam signified armor, as a dart, a blade, or sword; hence, to lam signified to disable, injure, maim, from which we have lame and limp.

Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.