Disloyalty is the name for that breaking of support: the act, or the habit, of not standing by your friends, your country, or your group. The person is disloyal; what they did is disloyalty. Selling a secret, changing sides, running down people who trusted you — those can all be called disloyalty.

Disloyalty is the name for that breaking of supportDisloyalty是那種「不再支持」的名稱: the act, or the habit, of not standing by your friends, your country, or your group也就是不挺朋友、不挺國家、不挺自己團體的那個行為，或那種習慣. The person is disloyal那個人是disloyal; what they did is disloyalty他做的那件事就是disloyalty. Selling a secret, changing sides, running down people who trusted you賣掉一個秘密、換邊站、說信任你的人壞話 — those can all be called disloyalty這些都可以叫做disloyalty

Though actually, like the adjective, it is a judging word, and the line is not always agreed.

Though actually不過其實, like the adjective跟形容詞disloyal一樣, it is a judging word這是個帶評斷意味的字, and the line is not always agreed而那條界線並不是大家都同意的

In history class it often means political betrayal. At home it might mean repeating something private.

In history class在歷史課上 it often means political betrayal它常常指政治上的背叛. At home在家裡的情境 it might mean repeating something private可能只是指把私事講出去

It is formal. When the hurt is sharp, everyday English often prefers betrayal. When it is milder, people just say that wasn't loyal.

It is formal這是個正式的字. When the hurt is sharp當傷害很深的時候, everyday English often prefers betrayal日常英文常常比較愛用betrayal. When it is milder當程度比較輕的時候, people just say that wasn't loyal大家就只說that wasn't loyal

Watch the grammar: disloyalty is a thing, not a person. You show disloyalty; you are not a disloyalty.

Watch the grammar注意一下文法: disloyalty is a thing, not a persondisloyalty是一件事，不是一個人. You show disloyalty你可以show disloyalty（表現出不忠）; you are not a disloyalty但你不會是a disloyalty