The quality or state of being flossy; the characteristic of resembling floss in texture, or of being flashy and showy.
From 'flossy' plus the noun-forming suffix '-ness' (from Old English '-nes'), which creates abstract nouns describing qualities or states.
The '-ness' suffix is one of English's most productive word-building tools—you can add it to almost any adjective to create a noun describing that quality, which is why speakers instinctively understand new words like 'flossiness'!
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