"to shake into a soft mass," 1875, from fluff (n.). Meaning "make a mistake" is from 1884, originally in theater slang. Related: Fluffed; fluffing.
"light, feathery stuff," 1790, apparently a variant of floow "wooly substance, down, nap" (1580s), perhaps from Flemish vluwe, from French velu "shaggy, hairy," from Latin vellus "fleece," or Latin villus "tuft of hair" (see velvet). OED suggests fluff as "an imitative modification" of floow, "imitating the action of puffing away some light substance." Slang bit of fluff "young woman" is from 1903. The marshmallow confection Fluff dates to c. 1920 in Massachusetts, U.S.
"botch, bungle," 1924, American English, of uncertain origin, perhaps suggested by fluff, flop, etc. Related: Flubbed; flubbing. As a noun, by 1952.
late 14c., "flax prepared for spinning," also "refuse of flax used as kindling," somehow from the source of Old English lin "flax" (see linen). Perhaps from or by influence of French linette "grain of flax," diminutive of lin "flax," from Latin linum "flax, linen;" Klein suggests from Latin linteum "linen cloth," neuter of adjective linteus.
Later "flocculent flax refuse used as tinder or for dressing wounds" (c. 1400). Still used for "flax" in Scotland in Burns' time. Applied to stray cotton fluff from 1610s, though in later use this is said to be American English.