被磨掉一層
兩個意思共用同一個動作，差別只在說的是「磨」還是「磨出來的那塊」。
noun · C1
The wearing away of a surface when something rubs hard against it, so that the surface is damaged or slowly disappears.
磨損
核心畫面
You can think of abrasion as one surface taking a layer off another by rubbing. Something hard and rough drags across something softer, and a little of the softer thing goes each time. The word can name that rubbing-away itself, or the bare place it leaves behind.
abrasion 可以想成「一個表面把另一個表面磨掉一層」。粗硬的東西擦過比較軟的東西，每擦一次就帶走一點。這個字既…更多收起
abrasion 可以想成「一個表面把另一個表面磨掉一層」。粗硬的東西擦過比較軟的東西，每擦一次就帶走一點。這個字既可以指「磨掉」這個過程，也可以指磨完之後露出來的那一塊。From the word’s history
Wiktionary traces it to Medieval Latin abrasio, a scraping, from Latin abradere, to scrape off — so the scraping action, not the mark, is what the word originally named.
來源資料把它追到中世紀拉丁文 abrasio（刮這件事），來自拉丁文 abrādō（刮掉）。也就是說，這個字最早指的是「刮」這個動作，而不是刮出來的痕跡。
Wiktionary (kaikki) entry for 'abrasion' supplied in the evidence packet: 'From French abrasion, from Medieval Latin abrasio (a scraping), from Latin abradō (scrape off).' (source_ref kaikki:3f6f69a190036ae4:13451841:32219)
Two branches
磨出來的那一塊
同一個動作，這次看的是結果，而且發生在皮膚上。
noun · C1
A sore patch on the skin where the top layer has been rubbed off against something rough or hard.
擦傷