(noun) A set of young birds that are hatched at the same time from the same parents. The term brood is most often applied to multiple offspring rather than a single hatchling. Different bird species may raise one or more broods per breeding season depending on the regional climate, food availability and bird health.
(verb) To sit upon eggs to hatch them. One or both parents may brood eggs during the incubation period to keep them protected and warm until they are ready to hatch.