We don't have synonyms for middle earth yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are middle ear, Middle East and middle-earth.
(n) :
(chiefly Norse mythology) synonym for Midgard, the world of traditional Germanic cosmology, conceived as a realm between heaven (Asgard) and hell (Niflheim).
(n) :
(fiction) Alternative form of Middle-earth: the setting of the Lord of the Rings series. [(fiction) The main setting of J. R. R. Tolkien's Lord of the Rings and other works.]
(n) :
Alternative letter-case form of Middle Earth. [(archaic) The Earth.]
(n) :
(chiefly Norse mythology) synonym for Midgard, the world of traditional Germanic cosmology, conceived as a realm between heaven (Asgard) and hell (Niflheim).
(n) :
(fiction) Alternative form of Middle-earth: the setting of the Lord of the Rings series. [(fiction) The main setting of J. R. R. Tolkien's Lord of the Rings and other works.]
(n) :
Alternative letter-case form of Middle Earth. [(archaic) The Earth.]