Taciturnity is the noun for being taciturn — the quality, in a person, of habitually saying very little. It names the trait rather than describing the person: his taciturnity, her famous taciturnity, a reputation for taciturnity. This is a distinctly bookish word, more formal even than taciturn, and you will meet it mostly in literature, biography, and older or more careful writing. It often turns up when a writer is weighing a character up — explaining that someone's silence was a lifelong habit, or hinting that it hid something. 'His taciturnity was taken for wisdom' is the kind of sentence this word lives in. Because it is abstract, it takes the shapes abstract nouns take: it can be broken by something ('his taciturnity finally broke'), it can be described ('a stubborn taciturnity'), and it can be given a cause ('a taciturnity born of years alone at sea'). In ordinary speech you would say 'he doesn't talk much' and everyone would understand you perfectly — reach for taciturnity only when you are writing, and only when the formal weight is what you want.

沉默寡言(的性格)、寡言。是 taciturn 的名詞，書面語，常出現在小說或人物描寫裡；口語直接說「他很少講話」就好。