核心畫面
Something small rubbing the same spot over and over — a tag scratching your neck, a grain of sand in your eye — until that spot becomes raw and you cannot ignore it.
有東西一直在磨、在搔、在戳同一個點。想像袖口的標籤整天摩擦你的脖子，或一粒沙跑進眼睛裡——單獨一下並不嚴重，但它不走…更多收起
有東西一直在磨、在搔、在戳同一個點。想像袖口的標籤整天摩擦你的脖子，或一粒沙跑進眼睛裡——單獨一下並不嚴重，但它不走，一次又一次地碰同一處，那個地方就開始發熱、發紅、坐立難安。irritation 就是這種「被反覆磨到受不了」的狀態；拉丁字根 irrītāre 原本就是「挑起、激起」，而英文把重點放在那個「一直挑、一直碰」的重複上。從皮膚被磨，到心裡被磨，走的是同一條路。From the word’s history
From Middle French irritation, from Latin irrītātiō, from irrītāre "to excite, provoke" (irritate + -ion). Latin named the provoking; English shifted the weight to the state left behind — skin that has been provoked becomes sore, and a person who has been provoked becomes annoyed.
英文 irritation 借自中古法語 irritation，源頭是拉丁語 irrītātiō，來自動詞 irrītāre「激起、挑動」；就構詞來看也可以拆成 irritate + -ion。有意思的是，拉丁語的 irrītāre 講的是「去挑、去撩」——把某個東西惹起來。英文承接了這個「挑動」的意思，但重心落在「被挑動之後那個受不了的狀態」：皮膚被一再挑動就發炎、發癢；人被一再挑動就煩躁。所以今天的 irritation 同時是身體的刺激感，也是心裡的惱怒，兩邊共用同一個「被一直挑」的來源。
Wiktionary 詞源欄（借自中古法語 irritation ← 拉丁語 irrītātiō ← irrītāre「to excite」；表層分析為 irritate + -ion），與本次 payload 提供的 etymology 說明一致
原始詞典資料5 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。
irritationnoun/ˌɪɹ.ɪˈteɪ.ʃən/
- 1
The act of irritating or annoying.
- What irritation causes you to be so moody?
- 2
The state of being irritated.
- It has already been established that the crew was competent and qualified for operation of AS66. With the exception of some overtones of irritation about the manner in which another aircraft, N799Y, affected the flight's progress into the Juneau area, the recorded cockpit conversation, in general, reflects a relaxed but businesslike atmosphere.
- Last spring, the periodical cicadas emerged across eastern North America. Their vast numbers and short above-ground life spans inspired awe and irritation in humans—and made for good meals for birds and small mammals.
- 3
A thing or person that annoys.
- 4
medicinephysiologysciencesA state of inflammation or of painful reaction to cell or tissue damage.
- 5
A condition of morbid excitability or oversensitiveness of an organ or part of the body; a state in which the application of ordinary stimuli produces pain or excessive or vitiated action.
- Hip pain is a common complaint in children and may indicate a very mild irritation in the hip joint or may be the symptom of a very severe abnormality
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。