1 brood (on/over/about sth) to worry, or to think a lot about sth that makes you worried or sad 忧思；沉思；苦想: to brood on a failure 为失败而耿耿于怀

2 (used about a female bird) to sit on her eggs （指雌鸟）孵卵，抱窝，孵蛋