Longman Dictionary of Contemporary English - fluff

~1 n 1 soft, light bits of thread or wool that have come from wool, cotton, or other materials 2 soft light hair or feathers, especially from a young bird or animal  (- compare down5 (2), - see also bit of fluff bit1 (19)) ~2 v 1 also fluff up, fluff out to make something soft appear larger by shaking or brushing it  (Sue fluffed the pillows for me.) 2 also fluff up, fluff out if a bird fluffs its feathers, it raises them and makes itself look bigger 3 informal to make a mistake or do something badly  (Rupert fluffed the catch. | fluff your lines (=make a mistake when speaking in a play))