You can picture a loose end: a rope, a cable, a pole with nothing holding it to anything else. Every use of the word is that same picture with a different kind of line missing — a rope to a post, a person to a partner, a person to an organisation.
可以想成一個鬆開的線頭。繩子、電線、支架，就放在那裡，沒有被接到任何東西上。這個字的每一個用法，都是同一張圖，只是少掉的那條線不一樣：有時候是繩子接到柱子的線，有時候是一個人牽到另一個人的線，有時候是一個人掛到某個單位的線。
From the word’s history
un- + attached: 'attached' is joined on, and 'un-' takes that away, leaving the free end.
un-（沒有）加上 attached（被接上）。attached 是「接上了」，un- 把它拿掉，剩下的就是那個鬆開的頭。
Wiktionary entry for unattached (packet etymology_text: 'From un- + attached.')
登入就可以看每一支怎麼連回核心畫面。