Passwords and account security

A clé de sécurité is one of the few keys on this page you can hold in your hand, which makes it the right place to collect what French does with the word once no door is involved. The one to learn first is mettre la clé sous la porte, word for word to put the key under the door. It is the gesture of a shopkeeper on the last evening, leaving the key for the landlord and walking off, and the phrase now means simply to go out of business — nothing in « key » carries that, and English reaches instead for « to shut up shop ». Next is clé en main, key in hand, said of a factory or a flat handed over ready to use: that is the ground « turnkey » covers, and one of the rare places where the two languages picked up the same object. Sous clé matches « under lock and key » almost word for word. And la clé de voûte is the keystone of an arch and, in an argument, the piece that holds everything else up. One noun, four settings, and only two of them a locksmith would recognise.