人的臉色與脾氣
這一支就是核心本身：一個人把自己關起來，氣在臉上，不在嘴上。
adjective · B2
Angry in a quiet, closed-up way: not shouting, but silent, heavy-faced and unwilling to talk, often because you feel something unfair has been done to you.
繃著臉悶著氣的
核心畫面
One way to hold sullen: someone has shut themselves off. The face is set, the mouth is closed, and the back is half turned to the room. Nothing is being said, yet everyone can feel that something is wrong and that it will not be explained. The word began as a word for being alone, and that shutting-off is still the picture inside it. Move the same picture onto the weather and you get the second use: a sky or a sea that has gone dark, low and silent, holding something back that has not arrived yet.
可以想成：sullen 是「有人把自己關起來」的樣子。臉繃著，嘴閉著，身體半轉開。沒有人開口，可是大家都感覺得到有事…更多收起
可以想成：sullen 是「有人把自己關起來」的樣子。臉繃著，嘴閉著，身體半轉開。沒有人開口，可是大家都感覺得到有事，而且那件事不會被說出來。這個字最早跟「獨自一個」有關，那份關上門的感覺一直留在裡面。把同一張臉搬到天上，就是第二個用法：天空或海面變暗、壓低、安靜下來，像是憋著什麼還沒放出來。From the word’s history
From Middle English soleyn, from Anglo-Norman soleyn 'alone', from Old French sole and Latin sōlus 'by oneself alone'. The meaning moved from 'single, alone' to 'morose' during the Middle English period.
來自中古英文 soleyn，再往上是盎格魯-諾曼語 soleyn（獨自的）、古法文 sole 和拉丁文 sōlus（一個人）。從「單獨」轉成「陰鬱、鬧脾氣」，是在中古英文時期發生的，所以「把自己關起來」這個畫面不是後來附會的比喻，而是這個字走過的路。
Wiktionary entry supplied in this packet (source_ref kaikki:3f6f69a190036ae4:1093405175)
Two branches
天色與海色
同一張關起來的臉，被放到天空和海面上：暗、低、不動，而且憋著還沒發生的事。
adjective · C2
Used about the sky, the sea or the weather: dark, heavy and still, in a way that makes you feel bad weather is coming.
陰沉欲雨的（天、海）