Middle-Earth.gen
middanġeardN (masc, a-stem)the middle dwelling (between heaven and hell), the earth, worldSource: https://bosworthtoller.com/22797Attested in Caedmon's HymnInflected formsmiddangeardes "Middle-Earth.gen" (oe-gen) in Sellic Spellmiddaneard "Middle-Earth.acc" (oe-acc) in Ælfric's Lives of Saints - Saint EugeniaParadigms
the middle dwelling (between heaven and hell), the earth, world