biodiversity UK /ˌbaɪə(ʊ)daɪˈvɜːsɪti/US /ˌbaɪoʊdəˈvɚsəti/ noun1 •The diversity (number and variety of species) of plant and animal life within a region.A drop in global biodiversity is putting our ability to produce food at risk, a new United Nations report warns. — 2019 formsbiodiversities