壓出來或切出來的凹
核心畫面最摸得到的樣子：往裡退的是實體的表面或邊緣。
noun · B2
A small dip, notch or hollow that has been cut or pressed into the surface or the edge of something.
凹痕；缺口
核心畫面
One way to hold this word: something that should run straight steps inward, and the step stays. A flat surface dips where a thumb pressed; an edge goes in and out where it was cut; a line of writing starts late instead of hard against the margin. In every case you are looking at the same thing — a place where the line moved in, and the gap it left behind.
可以想成：一條本來該筆直的邊，在某個地方往裡退了一塊，而且退進去就留在那裡。平面被拇指壓了一下，於是凹下去；邊緣被切…更多收起
可以想成：一條本來該筆直的邊，在某個地方往裡退了一塊，而且退進去就留在那裡。平面被拇指壓了一下，於是凹下去；邊緣被切過，於是一凹一凸；一行字沒有貼著左邊開始，而是往裡縮了一點。三種畫面看的其實是同一件事：某個地方往裡退，還有退出來的那塊空白。連法律條文裡的「款」，都是因為那一行縮進去，才得到這個名字。From the word’s history
From the verb indent plus -ation, which names either the action or what the action leaves behind. That double job is why the word covers both the act of indenting and the dip or gap itself.
由動詞 indent（把一行往裡推，或在邊緣切出缺口）加上 -ation 組成，而 -ation 同時可以指「這個動作」和「動作留下的東西」。這正好解釋了這個字的用法：它既可以指縮排或壓凹這件事，也可以指凹下去的那一塊、縮進去的那段空白。
Wiktionary etymology supplied in this packet: 'From indent + -ation' (source_ref kaikki:3f6f69a190036ae4:648127386:26164)
Two branches
文字往裡縮的那塊空白
同一個「往裡退」的動作，換成一行字。退進去的不是石頭或麵團，是文字的起點，而留下的那塊空白同樣被叫做 indentation。
noun · B2
The empty space left at the start of a line of writing, and also how wide that space is. You see it at the beginning of a paragraph and, in computer code, at the start of lines that belong inside something else.
縮排