From The Collaborative International Dictionary of English v.0.48:
Fluff \Fluff\, n. [Cf. 2d Flue. [root]84.]
1. Nap or down; flue[2]; soft, downy feathers.
[1913 Webster]
2. Hence: Anything light and downy, whose volume consists
mostly of air, such as cotton or down.
[PJC]
3. Something light and inconsequential; something not to be
taken seriously; -- used commonly of literary or dramatic
productions, and sometimes of people.
[PJC]
4. A mistake, especially in the recitation of lines in a
drama.
[PJC]
From The Collaborative International Dictionary of English v.0.48:
Fluff \Fluff\, v. t. & i.
To make or become fluffy; to move lightly like fluff.
--Holmes.
[Webster 1913 Suppl.]
From The Collaborative International Dictionary of English v.0.48:
Fluff \Fluff\, v. t.
To make a mistake in the performance of; -- used mostly of
lines in a drama; as, he fluffed the last line of the act.
[PJC]