The term “killing threshold” comes from the gaming field.
In a game context, it refers to the critical value: when a boss’s health drops below it, a berserk mode will be triggered, or players can launch an instant-kill attack.

It is a word describing a situation where in-game characters have absolutely no chance to regain health.
In 2025, this term was extended to describe the living conditions of ordinary Americans.
Relevant topics attracted attention on Chinese social media through live chats hosted by some Chinese immigrants and overseas students who had stayed in the US for many years.
Some of them got chances to meet ordinary people at the grassroots level, so they observed closely the terrible situations of a large number of bankrupt American middle-class families.

Later, many netizens reposted complaints and sad stories from ordinary American middle-class people, which gradually made the concept of America’s “killing threshold” more vivid and specific.

“斩杀线”一词源自游戏领域，在游戏语境中，它指BOSS血量低于临界值时触发狂暴机制，或玩家可发动一击必杀的阈值线，是形容游戏中角色完全没有“回血”余地的词汇，2025年该词被引申用以描绘美国普通人的生存状态， 相关话题在中国网络上被一些留美多年的华人和留学生以直播聊天的方式引发关注，他们中有人因各种机会接触到底层普通人，从而近距离观察到了大量美国中产阶层破产后的糟糕境遇。此后，有很多网友搬运了不少美国普通中产的吐槽和哭诉，逐步让这些美国“斩杀线”一词变得更加立体和具象化。