This name is a corruption of the old Orcadian/Pict, "Uuam", meaning cave; since translated into modern Irish as Uaimh and into Scottish Gaelic as Uamh. (The old Irish name for cave was prochóg, the old Scottish Gaelic name was brugh). On the coast of Fife, deep in the Pict heartland, beneath the ruins of MacDuff's castle, are some caves containing Pict drawings; and these caves gave Uuamais (place of the caves) or the Anglicized, Wemyss, its name. It became a surname of a cadet branch of the Royal house of Duff.
When senior male lines of the Duff family failed, that of the Wemyss became Chief of Scotland's senior clan, although they never reverted to the surname of MacDuff. Sir Michael Wemyss ensured the prosperity of his family by supporting the cause of Robert the Bruce. Thereafter, the name multiplied into many branches.
Its senior rose to the peerage in the reign of Charles I. In the 18th century, they emerged as the senior representatives of the ancient earldom of Fife. The Earl's eldest son supported the cause of Bonnie Prince Charlie, and afterwards was arrested. His younger brother assumed his titles.
This Earl adopted the name of Charteris, and it remains the name of the Earls of Wemyss to this day. The chiefship of the Clan MacDuff passed to a younger son of the 5th Earl. This family has not changed their name.
The 12th Earl of Wemyss, and 8th Earl of March, is Chief with the name of Charteris. He is President of the National Trust of Scotland, while his brother, Lord Charteris, is Chairman of the National Heritage Memorial Fund.