Of Scottish origin: Anglicized form of two different Gaelic names, Cinaed and Cainnech. The former was the Gaelic name of Kenneth mac Alpin (d. 858), first king of the united Picts and Scots. The latter survives today in Scotland as the common Gaelic name Coinneach. Since early in the 20th century Kenneth has been in regular use and enjoyed great popularity as a given name well beyond the borders of Scotland.
Welsh: descriptive nickname from Welsh llwyd ‘gray’. In Welsh the color term llwyd also includes shades of brown, and it is likely that, when used with reference to younger men, llwyd denoted brown or mouse-colored hair.