Picture a whole thing, and then one small piece broken off it. Now look only at that piece. Whatever is true of it and of nothing else is what this word is about. Sometimes the piece is what makes a thing unlike every other thing of its kind — the particularity of her writing. Sometimes it is a detail on a list, one of many small pieces. Sometimes it is the care of a person who will not skip a single piece. And in academic writing it is the plain fact of being one piece rather than the whole rule. The small part, held up on its own, runs through all of them.
Wiktionary traces the word through Middle French particularité and Late Latin particularitas to Latin particularis, from particula 'particle, small part', itself from pars 'a part, piece, portion, share'. The small part in the root is still the picture in every modern sense.
依 Wiktionary，這個字經中古法文 particularité 與晚期拉丁文 particularitas，來自拉丁文 particularis，再往上是 particula「小部分、微粒」，而 particula 來自 pars「部分」。字根裡的那一小塊，今天每個意思都還看得到。
Wiktionary etymology_text supplied in this packet (kaikki:3f6f69a190036ae4:1461667570)
Two branches
只屬於這一個
這一組把那一小塊當成「身分」來看：因為只有它有，所以它不能被同類的其他東西取代。
noun · C1
The quality that makes one person, place or thing unlike any other — the special character that belongs to that one thing alone. It is usually uncountable, but it is also used countably, meaning one special or odd feature that somebody has.
獨特之處
細部
這一組把那一小塊當成「數量」來看：一項一項的細節，以及一個不肯漏掉任何一項的態度。
noun · C1
One small detail of something. It is countable, and it is used mostly in formal or legal writing, usually in the plural: the particularities of the plan.
細節