The quality or state of being fashionable; the extent to which something follows current styles or is socially acceptable as stylish.
From 'fashionable' plus the suffix '-ness,' an older noun formation than 'fashionability,' both expressing the same concept in English.
Both 'fashionability' and 'fashionableness' exist in English, with '-ness' being older and more traditional, while '-ity' forms feel more technical—it's a quirk that English lets us express the same concept two different ways.
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