Fluff consists of soft threads or fibres in the form of small, light balls or lumps. For example, you can refer to the fur of a small animal as fluff .

If you fluff something that you are trying to do, you are unsuccessful or you do it badly.

If you fluff things such as cushions or feathers, you get a lot of air into them, for example by shaking or brushing them, in order to make them seem larger and lighter.