Definition of "Brood" :

noun: the young of an animal cared for at one time

verb: sit on (eggs)

"Birds brood."

verb: think moodily or anxiously about something

verb: be in a huff; be silent or sullen

verb: be in a huff and display one's displeasure

verb: hang over, as of something threatening, dark, or menacing

"The terrible vision brooded over her all day long."