1749, "two-edged broadsword of ancient Scottish Highlanders," from Gaelic claidheamh mor "great sword," from claidheb "sword" (compare Welsh cleddyf), possibly from PIE root *kel- (1) "to strike" (see holt) + mor "great" (compare Welsh mawr; see more). An antiquarian word made familiar again by Scott's novels; modern military application to pellet-scattering anti-personnel mine is first attested 1962.