The common name of the White Wizard, probably representative of his actual (unknown) Westron name in the way that “Frodo” represents the true Westron name Maura. As suggested by Christopher Tolkien, it is very likely based on a modernized form of Old English searu meaning “skill, cunning, cunning device” (UT/401 note #6). Hence in combination with “man” it is the equivalent of his Quenya/Sindarin names Q. Curumo and S. Curunír “Man of Skill” as pointed out by Hammond and Skull (RC/81).