Subversiveness is the quality of quietly working to weaken something powerful from the inside — a government, a school system, a religion, a set of rules everyone accepts. The key idea is *from underneath and out of sight*. A person who fights the government in the street is not being subversive; they are being open. A person who teaches students to doubt the government while pretending to teach history is. So the word carries a feeling of hidden intent, and that is why it usually sounds like an accusation: governments call people subversive, people rarely call themselves it. Though actually, the word has softened a lot in ordinary use. Today you will most often meet it about art, comedy, and advertising, where it is a compliment: "the subversiveness of her humour" means her jokes quietly attack ideas we never think to question. Nobody is worried about the government there. It just means the thing looks safe on the surface and is doing something else underneath. It is a formal, written word, and a heavy one — five syllables. Even writers who use *subversive* happily will often avoid *subversiveness* and write "how subversive it is" instead. If you can hear the difference, prefer the adjective; it almost always sounds better.

顛覆性（尤指暗中破壞體制的那種）。注意台灣講「顛覆」很常是稱讚，指某作品打破成規、很有創意；「顛覆國家」才是政治上的重罪。這兩種用法英文的 subversive 也都有，語氣要看場合。