Cubic is the word we use when we measure space inside something — volume. You multiply length by width by height. A box that is 2 metres by 2 metres by 2 metres has a volume of 8 cubic metres. You will see cubic centimetres, cubic metres, and in some countries cubic feet or cubic inches (sometimes written cu). That is the everyday sense. The same word can also mean shaped like a cube, and in maths a cubic equation has a number to the power of three. All of these sit next to the cube, the solid with six square faces.