Figurative use of a word, also known as a trope, is when a word or phrase is used in a non-literal sense. This can be done to create a more vivid image or to add emphasis to a point. For example, someone might say 'it's raining cats and dogs' to describe a heavy rainstorm. This phrase does not literally mean that cats and dogs are falling from the sky, but rather that the rain is coming down heavily.