MacTavish Modern Light Weight Tartan. The name is derived from the Gaelic name MacTamhais, meaning "son of Thomas". In the Lowlands the name takes the form of Thomson. The MacTavishes were numerous in Argyllshire, where the Clan Tavish of Dunardarie are said to have an ancient origin. There were MacTavishes in Stratherrick, Inverness-shire, who are claimed as septs of the Frasers of Lovat. The MacThomases of Glenhee, who are mentioned in the roll of the Clans in 1587, have a different origin. They were attached to the Clan Chattan.