Kennet is a very tricky one - lots of explanations all mixed up with pseudo celto-babble. Forget the fanciful link to the c**t word

Earliest form is Cyntetan c894, Cynete984, Kenete 1200. Cunetio was the early British river name. Once thought to mean "high" as in high king and likened to "Celtic" personal names like Cunobellin (Shakespeare's Cymbelin). Now discounted and thought to come from "cwn" which is Welsh for "dogs" (plural with the singular being "ci") A lot of ancient British words are really pidgin Latin and so "cwn" is clearly from the Latin "canis".

So Kennet could be the "river of the dogs". See - it's a kennel for the dogs that guarded the sheep in the Avebury sheep fold ;o)