rock bottom
触底，已经到达最低点
口语·形容最低谷
英文释义
the lowest possible point, the absolute bottom
例句
After losing his job and home, he hit rock bottom before starting to rebuild his life.
典故来源
源自地质学，'rock'指岩石，'bottom'指底部，比喻无法再下降的最低点。