Coombe or coomb or combe or comb is a country word for "valley" and an element in many English placenames, especially in the southwest. Not far up the Lim valley, for example, there are side-valleys called Holcombe, Rocombe, and Harcombe. Having learned in Wales that there is a Welsh word cwm also meaning "valley" and pronounced just the same, I assumed that this is the origin of the English word. But dictionaries say that coombe comes from the Old English cumb. A small etymological puzzle!

There was the Old English ("Anglo-Saxon") word cumb, "valley". And the proto-Celtic word kumbos, represented by the modern Welsh cwm, also "valley". And there is yet another English word coomb or comb, now rare, meaning a "bowl" or "tub", of which the Anglo-Saxon form was also cumb. It seems possible that the Saxon immigrants, finding the Celts using a word for "valley" that was pretty much the same as their own word for "bowl", took to calling valleys "bowls".

The Oxford English Dictionary says that whereas Dorset and Devon names like Branscombe and Widdecombe are from the Anglo-Saxon cumb, placenames in Cumbria (long a Celtic region) and southeastern Scotland such as Cumwhitton and Cumdivock were formed directly from the Celtic element.

Our common word for the implement we comb our hair with (pronounced with a different vowel, but likewise dropping the b) is of completely different origin: from Old English camb.