那條真的繩子：拴住與繫住
這一組就是核心畫面本身，繩子看得見、摸得到。
noun · B2
A rope or chain that an animal is tied to, so that it can walk about but only inside a small area around the place where the rope is fixed.
拴住動物的繩索
核心畫面
Picture a goat in a field with a rope from its neck to a post in the ground. The rope does not hold the goat still. It lets the goat walk, eat and lie down — but only inside the circle the rope can reach. Two things are true at the same time: free to move, and unable to leave. Every use of tether seems to grow from that double picture, and each one keeps both halves. What changes is what sits at each end of the rope: a goat and a post, an astronaut and a spacecraft, a laptop and a phone, a person and the town they grew up in. And when the animal has walked as far as the rope allows, the line is stretched tight with nothing left to give — that is the picture behind being at the end of your tether.
田裡的一隻羊，脖子上一條繩子綁在地上的木樁。繩子不是要牠不能動。牠可以走、可以吃草、可以躺下——但只能在繩子畫出的那…更多收起
田裡的一隻羊，脖子上一條繩子綁在地上的木樁。繩子不是要牠不能動。牠可以走、可以吃草、可以躺下——但只能在繩子畫出的那個圓圈裡。兩件事同時成立：能動，卻離不開。tether 的每一個用法，就像都從這個雙面畫面長出來，而且兩半都留著。換掉的只是繩子兩端綁著誰：羊和木樁、太空人和太空船、筆電和手機、一個人和他長大的小鎮。而當動物已經走到繩子的最遠處，繩子拉得筆直、再也放不出一寸——那就是 at the end of your tether 背後的畫面。From the word’s history
Wiktionary traces tether through Middle English tether/teder to Old English *tēoder and Old Norse tjóðr, from Proto-Germanic *teudrą, glossed there as 'rope; cord; shaft'. It records the earlier origin as uncertain, suggesting a possible root meaning 'to tie' or 'to pull'. So the oldest recorded meaning is simply the rope itself, which is the object the modern picture still starts from.
依 Wiktionary 的記載，tether 經由中古英語 tether／teder，可追到古英語 *tēoder 與古北歐語 tjóðr，再往上是原始日耳曼語 *teudrą，該處的解釋就是「繩、索」。更早的來源記為不確定，只推測可能連到「綁」或「拉」的字根。也就是說，有記載的最早意思就是那條繩子本身，正好是今天所有用法的起點。
Wiktionary (kaikki:3f6f69a190036ae4:926937972:25330), etymology_text supplied in the evidence packet; the packet itself marks the pre-Germanic origin as uncertain
Three branches
看不見的繩子：牽住與連上
繩子拿掉了，圓圈還在。這一組用同一個畫面講「能動但離不開」，或是「一端接著另一端」。
verb · C1
To fasten something to a fixed point with a rope or line; also, to keep a person or thing joined to something so that they cannot move far from it.
繫住；把…牽住
繩子的盡頭：拉到底了
同一條繩子，但看的是它的最遠處——動物再往前一步也走不了的地方。
noun · C1
If you are at the end of your tether, you are so worried, tired or upset that you feel you cannot deal with a hard situation any longer.
撐到極限、快受不了