Diving

Diving is applied physics with very narrow tolerances, and the language matches. La parada de seguridad is not a suggestion but part of the profile, and la reserva de aire is not an emergency cushion but a planned quantity. The seventh entry, el lastre ajustado, is the weight a diver carries to stop floating — and the noun has a second life in which it means the opposite of what English hears. « Ballast » in English is a good thing: it steadies a ship, and somebody with ballast is somebody hard to upset. El lastre keeps the literal sense, but its figure of speech went the other way — la deuda es un lastre para la empresa means the debt is dragging the company down, and soltar lastre is to let something go in order to move again. Both languages saw the same lead block at the bottom of the boat; one thought of steadiness and the other of weight.