One way to hold this word: picture money coming in through a door, and then point at whatever is bringing it. Whatever your finger lands on is the earner. Usually it lands on a person who works. Sometimes it lands on a shop, a crop, a weekend stall. The word never describes the thing itself, only its job of bringing money in — which is why it nearly always needs a word in front telling you how much, or what kind.
From the word’s history
The source builds the word as earn + -er. The -er ending names the one that does the action, and in English it does not have to be a person (compare opener, cooker), which is exactly why both a worker and a business can be an earner.
來源把這個字拆成 earn ＋ -er。-er 指「做這個動作的那一個」。英文裡這個 -er 不一定是人，像 opener、cooker 都是東西。這正好說明為什麼一個上班的人和一門生意，都可以叫 earner。
Wiktionary (kaikki snapshot 3f6f69a190036ae4), earner: etymology tree 'English earn … English -er … English earner. From earn + -er.'
登入就可以看每一支怎麼連回核心畫面。