The term 'structure supporting power cables' can be summarized as a pylon, which is a five-letter word. A pylon is a tall structure that is used to support power cables, such as those used in electrical transmission lines. It is usually made of metal and is designed to be strong enough to withstand the weight of the cables and any other forces that may act upon it. Pylons are often seen along highways and in other areas where power cables need to be supported.