brood

Brood is a term with several related senses in biology and animal care. As a noun, it commonly denotes the young produced by a single reproductive event, such as a brood of chicks or ducklings. It can also refer to the act of sitting on eggs to incubate them, or to the group of offspring produced in one nesting attempt. As a verb, brood means to dwell on something in a moody or persistent way.

In birds, a brood is the offspring hatched from a clutch within a single nesting attempt. Brood size varies by species. Broodiness is the tendency of hens to sit on eggs and incubate them rather than forage.

In apiculture, brood refers to the developing life stages—eggs, larvae, and pupae—within the hive's brood area, in contrast to honey stores. The queen lays eggs in brood cells on brood frames; workers care for the brood until emergence. The health of the brood is central to colony strength, with diseases and temperature management affecting development. The term brood frame or brood nest describes where these developing individuals are kept; drones and queens develop in specific brood areas.

Brood parasitism is a strategy by which some species lay eggs in the nests of other species to be raised by the host. The verb brood can also refer to persistent worrying or musing.

Etymology traces to Old English bred or brood meaning offspring; cognates exist in other Germanic languages.