Whitsome derives from Old English hwit-husum "at the white houses". This may refer to white stone buildings, or houses painted white. The name has been recorded as the following over the centuries:
æt hwitum husum , 984 (literally "at the white houses, -um being dativeplural).
Huuithusum, 1038 (double u was written since "w" could not be pronounced by the author)