If someone is self-possessed, they stay calm, sure, and in charge of their feelings when the room goes wrong — a hard question, bad news, a sudden fright.

if someone is self-possessed如果一個人self-possessed they stay calm, sure, and in charge of their feelings他們會保持冷靜、篤定，掌控自己的情緒 when the room goes wrong當現場出狀況時 a hard question困難的問題, bad news壞消息, a sudden fright突如其來的驚嚇

English uses this as praise. You are saying you admire the way they hold themselves. It often describes a voice, a face, or a manner in public: interviews, meetings, emergencies.

English uses this as praise英文把這個字當稱讚用 you are saying you admire the way they hold themselves表示你欣賞他們自持的樣子 it often describes a voice, a face, or a manner in public它常用來形容公開場合的聲音、表情或舉止 interviewsinterviews, meetingsmeetings, emergenciesemergencies

Though actually, it does not mean the person feels nothing. It means they still have hold of what they feel, so other people see control rather than panic.

though actually不過其實 it does not mean the person feels nothing它不是說這個人沒有感覺 it means they still have hold of what they feel而是說他們依然掌握著自己的感受 so other people see control rather than panic所以別人看到的是掌控而不是慌亂

The word is a little formal, even a little old-fashioned; friends might just say calm or composed.

the word is a little formal, even a little old-fashioned這個字有點正式，甚至有點老派 friends might just say calm or composed朋友之間可能就直接說calm或composed

One messy corner: possessed by itself can mean taken over by a spirit, which is a ghost story. Self-possessed has nothing to do with that. It is the older idea of possessing yourself — you, not fear, are in charge.

one messy corner有個容易搞混的地方 possessed by itself can mean taken over by a spirit單獨的possessed可以指被鬼魂附身, which is a ghost story那是鬼故事的說法 self-possessed has nothing to do with thatself-possessed跟那個完全無關 it is the older idea of possessing yourself它是比較舊的「擁有你自己」的概念 you, not fear, are in charge是你、而不是恐懼，在掌控