Broody comes from brood (Old English brōd, 'offspring, hatching') + the adjectival suffix -y. The 'inclined to incubate eggs' sense (of a hen) is primary; the human 'moodily silent' sense is figurative. The historical trail runs through brōd in Old English. Morphologically, broody is transparent: it draws on brood (Old English brōd, 'offspring, hatching') + the adjectival suffix -y. Used as an adjective, broody now means "moodily silent or melancholy; (of a hen) inclined to incubate eggs", so the present definition can be read against the older forms and meanings. The same lexical family is also visible in derived forms such as broodily and broodiness and related forms such as brood and brooding. The modern word remains analyzable through its parts, which makes the semantic connection unusually direct.