Welding

The second entry is metal de base, and the obvious English rendering is the one to be careful with. Word for word it gives « base metal », and that phrase is already spoken for. In English, « base » in front of the name of a metal is not a position but a verdict: the base metals are the common ones, copper, lead, tin, zinc and iron, as against the noble metals, gold, silver and platinum. The sense is centuries old, it belongs to assaying and to coinage, and it is alive on any page about jewellery or bullion. British welding papers therefore leave it alone and write « parent metal » instead, the metal the joint grows out of, as against the filler that is added to it. American practice does say « base metal » and is understood everywhere, so a reader meets both, but only one of the two carries no older meaning. Metal de base has no such echo at all: base there is simply what the rest stands on, and nothing in the word says cheap.