拿杯子當尺：小到可以捧著走
同一個杯子，這次不是拿來裝東西，而是拿來比大小。因為茶杯又小又輕，英文就用它當量尺，說某隻寵物小到差不多能放進去。
adjective · B2
Put in front of the name of a pet animal, teacup says that the animal is very small — small enough for a person to pick up and carry around.
茶杯型的（超小型寵物）
核心畫面
One small thin cup with a handle, sitting on its . It is the cup you actually lift and drink from, and it is small and light enough to hold in one hand. From that single object two other uses grow: how much it holds, and how little space it takes up.
可以想成桌上一個又薄又小的杯子，有一個把手，下面墊著一個小碟子。它就是你真正端起來喝的那一個。整個字的其他用法，都可…更多收起
可以想成桌上一個又薄又小的杯子，有一個把手，下面墊著一個小碟子。它就是你真正端起來喝的那一個。整個字的其他用法，都可以從這個小杯子長出來。往裡面看，它是一個「裝得下多少」的量：a teacup of milk。往外面看，它是一把尺，用來說某個東西小到什麼程度：teacup dog、teacup pig。這是一種方便記憶的看法，不是在說這個字的歷史一定是這樣走的。From the word’s history
The packet's source entry gives the word as simply tea + cup, so the modern core is the compound read literally: a cup for tea.
來源資料寫的是 tea + cup，所以這個字的核心就是字面上那個意思：裝茶的杯子。後面兩種用法都還站在這個杯子上面。
Wiktionary etymology supplied in this packet: "From tea + cup." (source_ref kaikki:3f6f69a190036ae4:989564687)
From the picture
Also in this word
noun · A2
A small cup that you drink tea from. It usually has a handle, and it usually sits on a small plate called a saucer.
茶杯
noun · B1
The amount that a teacup holds, used as a rough measure of liquid or of dry food such as rice or flour.
一茶杯的量