Mainly U.S.: medieval vernacular form of Randolf. This was in common use as a given name into the 17th century and gave rise to a surname. In modern use the given name is often a transferred use of this surname.
Irish: Anglicized form of Gaelic Ó Tuathail ‘descendant of Tuathal’, an old Celtic personal name composed of the elements tuath ‘people’ + gal ‘mighty’. This is the name of distinct families in Leinster and Ulster.