驢子，以及從驢子長出來的罵法
這一家就是原本那條線：先有動物，再有拿動物講人的說法。
noun · C1
A donkey: a grey or brown animal like a small horse, with long ears, kept for carrying people and loads. This is an old word for the animal; today people say 'donkey'.
驢子
這個拼法底下其實是2個不同的字，意思沒有關係， 只是長得一樣。下面分開列出來。跳到 驢子 · 屁股
1
ass
noun核心畫面
One way to hold this word: a donkey standing on the road with a load on its back. It can walk. It has decided not to. You pull, it stays. English has used that picture about people for a very long time — not someone who cannot understand, but someone whose stubborn, behaviour leaves everyone else stuck.
可以想成路邊那頭馱著東西的驢子：耳朵長、腳步慢，你拉牠，牠就是不動。牠不是走不動，是牠決定不走。英文很早就把這個畫面…更多收起
可以想成路邊那頭馱著東西的驢子：耳朵長、腳步慢，你拉牠，牠就是不動。牠不是走不動，是牠決定不走。英文很早就把這個畫面拿來講人——不是說對方笨到學不會，而是說對方那種固執又不長眼的做法，把旁邊的人全卡住了。所以這一支底下只有兩個意思：動物本身，以及從動物長出來的罵人話。From the word’s history
Wiktionary traces this ass to Old English assa, ultimately from Latin asinus, and notes that the 'stupid person' use goes back to antiquity, where Latin asinus already meant a slow-witted person.
根據 Wiktionary，這個 ass 來自古英語 assa，最終源頭是拉丁文 asinus（驢子）。同一份資料也指出，用驢子罵人這件事很早就有了：拉丁文的 asinus 本身就能指反應慢的人。
Wiktionary (kaikki extract, source_ref kaikki:3f6f69a190036ae4:94117347), etymology 1 for 'ass'
One branch
A second word, same spelling
2
ass
noun, adjective, particle核心畫面
A different word that happens to be spelled the same. One way to hold it: the part at the back of you that meets the chair. American speech keeps reaching for it, because it is the part that moves first when somebody is pushed, pulled or called over — so it ends up standing for the whole person, and then for how bad a thing is.
這是另一個字，只是在美國拼成同樣的樣子。可以想成身體最後面、坐下來會碰到椅子的那一塊。美式口語很愛用它，因為一個人被…更多收起
這是另一個字，只是在美國拼成同樣的樣子。可以想成身體最後面、坐下來會碰到椅子的那一塊。美式口語很愛用它，因為一個人被推、被叫、被催的時候，最先動的就是那裡——講久了，那一塊就代表整個人。再往外長，它還變成評價（很爛）和加強語氣（超大一隻）。這一整家都很粗，用在什麼場合比意思本身更要小心。From the word’s history
Wiktionary records this ass as a variant of arse used chiefly in North America, from Old English ærs, and notes it arose as a pronunciation spelling rather than as a polite substitute.
根據 Wiktionary，這個 ass 是 arse 的變體，主要用在北美，往上追到古英語 ærs。同一份資料還特別註明：它不是為了避諱才出現的委婉說法，而是照著念法拼出來的寫法。
Wiktionary (kaikki extract, source_ref kaikki:3f6f69a190036ae4:94183309), etymology 2 for 'ass'
From the picture
身體上的那一塊
最字面的用法，其他幾個都從這裡長出去。
noun · B1
The part of your body that you sit on. This is a rude everyday word in American English; it is very common in speech, films and songs, but people use 'bottom' or 'backside' when they want to be polite.
屁股
Also in this word
noun · B2
Used after 'my', 'your', 'his' and so on to mean the person themselves, especially their body: 'get your ass over here' means 'get yourself over here'. It can also mean the person's safety, job or future, as in 'it's my ass on the line'.
（你我他）這個人；小命、飯碗