ecospherePronunciation: /ˈiːkəʊsfɪə/Translate ecosphere | into German Definition of ecosphere noun the biosphere of the earth or other planet, especially when the interaction between the living and non-living components is emphasized. Astronomy the region of space around a star where conditions are such that planets are theoretically capable of sustaining life. ecosphere in other Oxford dictionaries Definition of ecosphere in the US English dictionary