Groups of young birds hatched at the same time.

• The young of egg-laying animals, or a family's children.
• The eggs and larvae of social insects kept together in a colony.

Third-person singular of brood: thinks gloomily or anxiously about something.

• Dwells on a problem or slight for a long time.

Third-person singular of brood: sits on eggs to hatch them.

• Protects or warms young while they develop.