asthenosphere

== English == === Etymology === From astheno- +‎ -sphere. === Pronunciation === (UK) IPA(key): /asˈθɛnə(ʊ)sfɪə/ === Noun === asthenosphere (plural asthenospheres) (geology) A portion of the Earth's upper mantle, below the lithosphere. Holonyms: upper mantle, outer mantle < mantle < Earth ==== Derived terms ==== ==== Translations ====