- An assembly of components to fulfil particular requirements.
Materials are just materials before they are put together in the desired way to form a structure. The word is used also when referring to the assembly of the atoms and the molecules inside a material, and indeed any arrangement of discrete parts. Bridges are structures of great variety, though all serve the same purpose, providing access over some obstacle. Modern motorways require hundreds of bridges of more-or-less standard design; but elsewhere there is entrancing diversity.