Genetics and inheritance

The fourteenth entry is la double hélice, and the noun inside it does a job in French that « helix » has never been asked to do in English. Our word is a curve and nothing else. It is the shape of a spring, the outer rim of the ear that an anatomist calls the helix, and the coil a chemist draws for a protein. Outside those it is not used at all, and no mechanic has ever said it. L’hélice covers the curve too, and then walks straight into the workshop. It is the propeller of a ship, l’hélice du bateau. It is the propeller of an aircraft, so that un avion à hélices is a propeller plane and le pas de l’hélice is its pitch. A spiral staircase can be un escalier en hélice. A sentence carrying hélice is therefore about a blade far more often than about a curve, and the safe reflex is to look for water or air before reaching for « helix ». On this page the rare reading is the right one, which is what the adjective is doing there: double announces the molecule and rules the boat out.