Stylishness is the quality of being stylish — the fact that a person, a thing, or a piece of work has style. It is the noun you use when you want to talk about that quality itself rather than describe something with it: 'the stylishness of her writing', 'a car admired for its stylishness', 'there is a certain stylishness about him'. Because it is an uncountable quality noun, it takes no 'a' and no plural: you can have great stylishness, a lot of stylishness, but not 'two stylishnesses'. It appears most in reviews, design writing, and fashion journalism, where the writer is assessing something. In ordinary conversation people avoid the word — it is long and slightly formal — and say 'she has great style' instead, which means the same thing. That gives you a useful pair: 'style' is the thing you have, 'stylishness' is the measured quality of having it, the word a critic reaches for. Note that stylishness is usually about surface and taste. Calling a novel stylish praises how it is written; it does not say the story is deep. Sometimes a critic means exactly that, and 'mere stylishness' is a real and quite cutting phrase.

時髦、有型、有品味（指那份「講究」的特質本身）