noun / verb
fluff
FLUF/flʌf/
Soft, light material with an airy texture.
Airy wisps of pale fluff form a loose mound beside scattered tufts.

Etymology
Fluff is apparently a variant of floow, meaning down or nap. The OED suggests an imitative modification evoking the action of puffing away a light substance.
In context
I think the majority of writers would agree that fluff is really bad in a story.
More examples
- A ball of fluff collects in the dryer filter.
- I fluff the pillows before making the bed.
- She fluffs the cooked rice with a fork.
Forms
fluff · fluffs · fluffed · fluffing
fluffy adjective — Soft, light, and full of air.
fluffiness noun — The quality of being soft and airy.