BLACK BOX • DICCIONARIO INGLES.COM • Definition of Black box

... of hydrogen, for instance, closer and closer together. At the end of the last century, the Bending Converter had almost wrecked the economy of the entire world, since it gave to the world a source of free energy. Sam Bending's "little black box" converted ordinary water into helium and oxygen and energy—plenty of energy. A Bending Converter could be built relatively cheaply and for small-power uses—such as powering a ship or automobile or manufacturing plant—could literally run on air, since the moisture content of ordinary ...

— Unwise Child • Gordon Randall Garrett