obesity UK /ə(ʊ)ˈbiːsɪti/US /oʊˈbisɪti/ noun1 •The state of being obese.The fowls, ducks, and goats all looked fat and thriving on the refuse food of a dense population, and the Chinamen's pigs were in a state of obesity that foreboded early death. — 1869 formsobesities