真的沒有顏色
這一組就是字面意思：眼睛看不出任何顏色。
adjective · B1
Having no colour at all, or almost none, like clean water or air; you can usually see straight through it.
無色的
核心畫面
Think of a drawing with all its lines finished and no paint on it. Everything is there — the shape, the detail, the outline — and still the eye slides off it. Colourless is that missing paint. Sometimes the thing never had colour, like water or air; sometimes the colour has drained out of it, like the blood leaving a face.
colourless 可以想成一張線條都畫好、卻還沒上色的圖。形狀在、細節也在，但眼睛就是留不住。這個字說的就是那層…更多收起
colourless 可以想成一張線條都畫好、卻還沒上色的圖。形狀在、細節也在，但眼睛就是留不住。這個字說的就是那層沒有塗上去的顏色。有時候是本來就沒有，像水和空氣；有時候是原本有、後來退掉了，像一張被嚇白的臉。From the word’s history
The packet's etymology tree gives colour (from Latin color, via Old French and Middle English) plus the suffix -less (Old English -lēas), so the word literally says 'without colour'.
來源的字源樹顯示這個字是 colour（經古法文、中古英語，源自拉丁文 color）加上字尾 -less（古英語 -lēas），字面就是「沒有顏色」。
Wiktionary (kaikki extract, packet field etymology_text: etymology tree for colour + -less)
Three branches
顏色退掉了
同樣是沒有顏色，但這裡的重點在「本來有、現在沒了」，所以它成了一個警訊。
adjective · B2
If someone's face, lips, skin, hair, or eyes are colourless, they look very pale, usually because the person is ill or frightened.
蒼白的／沒血色的
比喻上的沒有顏色
顏色被借去代表別的東西——有時代表吸引力，有時代表陣營；一旦少了，就用同一個字。
adjective · B2
Not interesting or exciting, with nothing that makes people notice or remember it — often because everything about it is plain and much the same.
乏味的／平淡無奇的
原始詞典資料4 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。
colourlessadj/ˈkʌlə(ɹ).ləs/
- 1
Having little or no colour.
- The servant to whom he put this question was a young fellow with chubby cheeks, small, dull eyes, and a round chin, covered with a colorless down.
- Behind him the hills are open, the sun blazes down upon fields so large as to give an unenclosed character to the landscape, the lanes are white, the hedges low and plashed, the atmosphere colourless.
- 2
Water white.
- 3
Lacking in interest or variety.
- 4
governmentpoliticsNeutral in opinion or allegiance; centrist
- They cannot, of course, assume a colourless position because they cater to the radical rank and file and would be branded renegades.
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。