Other forms: brooding; brooded; broods
A brood is a group of young born at the same time — like a brood of chicks — but your parents might use the word for you and your siblings: "We're taking the whole brood to the movies tonight."
Brood is also what a chicken does when she sits on her eggs to hatch them. You can also brood, when you worry and sulk and dwell on something obsessively — maybe as tedious as sitting on eggs, but no chicks when you're done. Things like clouds or silence can also brood, hanging over something ominously, as a storm that broods over the sea, sending fishermen scurrying for safety.