1 down, fuzz, feather(s), thistledown, floss, lint, dust, dust-ball, fuzz ball:
Be sure you clean the fluff from under the beds.
2 bit of fluff. poppet, girl (friend), mistress, Slang bit of all right, (bit of) crumpet, (bit of) skirt or stuff, Old-fashioned Brit popsy:
Bickerley keeps some fluff on the side.
3 blunder, error, slip, mistake, Colloq howler, Brit bloomer, US and Canadian blooper:
They showed a video of the fluffs actors make during recordings.
4 muddle, spoil, ruin, make a mess of, bungle, botch, Colloq foul up, screw up, mess up, US snafu, Slang Brit cock up, balls up, US ball up, Taboo fuck up:
I have a funny story about how Barrymore fluffed Hamlet's soliloquy.
5 fluff up. puff up, shake out or up, aerate:
He doesn't like the pillows on his bed fluffed up.