One picture holds this word: a liquid you can actually put in your mouth and swallow. Drink supplies the action, and -able opens the door. From that picture the word splits along the only two questions people ask before they drink something — will this hurt me, and do I want another sip?
可以想成一個很簡單的畫面：一杯液體，你真的能把它喝下去。drink 提供動作，-able 打開那扇門，字面就是「可以被喝的」。人在喝東西之前，其實只問兩件事：喝了會不會出事，還有好不好喝。drinkable 的用法剛好就沿著這兩個問題分開來：一邊回答安不安全，一邊回答順不順口。把形容詞直接當名詞用的 drinkables，則是從同一個畫面退一步，把「能喝的那些東西」整批指出來。
From the word’s history
The source records drinkable in Middle English as drinkable, drynkeable, equivalent to drink + -able.
來源記錄 drinkable 在中古英文就有 drinkable、drynkeable 的寫法，組成方式是 drink 加 -able。所以「可以被喝的」不只是我們事後編出來的聯想，它本來就是這個字的拼法。
Wiktionary, "drinkable"
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