claymore - 1722, from Gael. claidheamh mor "great sword," from claidheb "sword," from I.E. base *kel- "to strike" + mor "great." An antiquarian word made familiar again by Scott's novels; modern military application to pellet-scattering explosive is first attested 1962.
From the fun with [link|http://www.geocities.com/etymonline/|etymology] department.