You can picture two things standing side by side. One of them has something the other simply does not have. Point at that one thing, and you are pointing at a peculiarity. The picture has two halves that travel together: it belongs to this one alone, and because nobody else has it, it looks a little odd. Follow the first half and you get a distinctive feature; follow the second half and you get a strange habit, or the feeling of strangeness itself.
From the word’s history
Wiktionary records peculiarity as peculiar + -ity, with -ity coming through Old French from Latin -itas. The core image is already in that shape: take what is one's own, and turn it into a thing you can name.
Wiktionary 記錄 peculiarity 由 peculiar 加上 -ity 組成，-ity 經古法文來自拉丁文 -itās。這個結構本身就是核心畫面：把「屬於某人自己的」那一點，變成一個可以指著講的名詞。
Wiktionary (kaikki extract supplied in packet, source_ref kaikki:3f6f69a190036ae4:655953901:15113)
登入就可以看每一支怎麼連回核心畫面。