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.
English: topographic name or metonymic occupational name for someone who lived by or worked at a barn or barns, from Middle English barn ‘barn’, ‘granary’. In some cases, it may be a habitational name from Barnes (on the Surrey bank of the Thames in London), which was named in Old English with this word.