From Old Galician-Portuguese traado, independently attested (14th century); from Late Latin taratrum (“auger”), used by Isidore of Seville. Probably from Paleo-Hispanic or from Proto-Celtic *taratrom, alternatively from Ancient Greek τέρετρον (téretron, “borer, gimlet”), both from Proto-Indo-European *térh₁-tro-. Cognate with Portuguese trado, Spanish taladro, Catalan traire, French tarière, Old Irish tarathar, Old Welsh tarater, Breton tarar.