Mainly North American: of uncertain origin. It is found among Jews as well as gentiles. Among the latter it is generally from the name of the English county, either directly or as a transferred use of the surname, which derives from a British tribal name said to mean ‘worshippers of the god Dumnōnos’.
English and Scottish: patronymic from a Middle English male personal name: in most cases probably Allen, but other possibilities include a variant of Ellis or a short form of Alexander. In some instances, it may be from a female personal name, Alise or Alice (see Allis).