真的很髒
這一族就是核心畫面的字面版：實體的髒，髒到讓人皺眉頭。
very dirty · adjective · C1
Very dirty, often so dirty that people are shocked or a lot of cleaning is needed.
骯髒
核心畫面
A useful picture: dirt so thick it makes you recoil — not 'needs a wipe' but 'I don't want to touch that'. The word carries the speaker's disgust, and that disgust is what travels: to language that feels dirty, to a look that feels ugly, to weather that leaves everything wet and muddy, and finally to a bare .
髒到讓人下意識往後退一步。不是「桌上有點灰、擦一下就好」，而是那種黑掉的鍋底、多年沒洗的窗簾、你不太想用手碰的東西。…更多收起
髒到讓人下意識往後退一步。不是「桌上有點灰、擦一下就好」，而是那種黑掉的鍋底、多年沒洗的窗簾、你不太想用手碰的東西。dirty 只是陳述髒，filthy 多了說話者的一股嫌惡——這股「噁心、受不了」的感覺才是這個字真正的核心。所以它後來跑到別的地方時，帶走的不是「泥巴」，而是那個嫌惡：讓人反感的話、讓人不舒服的臉色、讓人狼狽的天氣，最後乾脆變成純粹加強語氣的字。From the word’s history
filthy is Middle English filthi, simply filth + -y: 'having the quality of filth'. Filth itself goes back to Old English fȳlþ, formed from fūl 'foul, rotten' — so the word is built on rot and stink, not on mere dust, which is why it has always carried revulsion rather than neutral description.
filthy 在中古英語就是 filth（污穢）+ -y，字面上「具有污穢性質的」。而 filth 再往前是古英語 fȳlþ，由 fūl（腐臭的、令人作嘔的，也就是今天的 foul）構成。也就是說，這個字的根不是「灰塵」而是「腐爛發臭」——它從一開始講的就不是乾淨與否，而是會不會讓人反胃。這解釋了為什麼 filthy 從頭到尾都帶著說話者的厭惡，也解釋了它為什麼能自然地拿去罵髒話、罵臉色。
Payload etymology (Middle English filthy = filth + -y), extended with the standard derivation of filth from Old English fȳlþ, an abstract noun formed on fūl 'foul'.
Four branches
髒在話語與心思上
把「髒」從東西移到語言和念頭上：講出來的話讓人像碰到髒東西一樣不舒服，於是同一個字直接拿來用。
sexually rude or offensive · adjective · C1
Rude and offensive in a sexual way, used about language, jokes, pictures, or thoughts.
下流
髒在臉色與天氣上
這裡不再有實際的髒污，留下的只是核心那股「讓人受不了」的感覺，被拿去形容人的臉色和天氣的糟糕程度。中文的「一臉黑」「鬼天氣」是很接近的直覺。
showing anger (filthy look) · adjective · C1
Showing that you are very angry or annoyed, used especially about a look, mood, or temper.
惡狠狠
純加強語氣（副詞）
強烈的情緒字很容易退化成純粹的放大器（就像 terribly good、awfully nice）。filthy 在這兩個固定搭配裡就走完了這條路：它不再說什麼髒，只負責喊「極度」。
filthy dirty · r · C1
Used before dirty to mean extremely dirty.
極髒
原始詞典資料6 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
filthyadj/ˈfɪlθi/
- 1
Covered with filth; very dirty.
- The coaches were filthy outside and did not appear to have been painted or washed for years. Inside there were uncomfortable seats covered with a cane-like material.
- 2
Obscene or offensive.
- Filthy smirking Pat Robertson has come in second in the Iowa Republican caucuses.
- 3
Very unpleasant or disagreeable.
- Oh, that filthy dream again. Nightmares are bad enough but when it comes to night-toads—!
- 4
slangAngry; upset; severely annoyed.
- Terrific fun it was. My best mate saved me, and the teacher was filthy.
filthyverb/ˈfɪlθi/
- 1
To make very dirty; to saturate something with dirt.
- In the years following World War Two, Americans cut down vast forests, built thousands of factories, assembled millions of atmospherically toxic automobiles, and filthied the water throughout North America.
- 2
To cover in filth.
- He shouldered his way inside, filthying his T-shirt on the charred wood.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。