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 earth, middle-east and middle-ear.
(n) :
(fiction) The main setting of J. R. R. Tolkien's Lord of the Rings and other works.
(n) :
Alternative form of Middle Earth: the Earth. [(archaic) The Earth.]
(n) :
(fiction) Alternative letter-case form of Middle-earth: the setting of the Lord of the Rings mythos. [(fiction) The main setting of J. R. R. Tolkien's Lord of the Rings and other works.]
(n) :
Alternative form of Middle Earth: (archaic) the Earth; (Norse mythology) Midgard. [(archaic) The Earth.]
(n) :
(fiction) Alternative letter-case form of Middle-earth. [(fiction) The main setting of J. R. R. Tolkien's Lord of the Rings and other works.]
(n) :
Alternative spelling of Middle Earth. [(archaic) The Earth.]
(n) :
(fiction) The main setting of J. R. R. Tolkien's Lord of the Rings and other works.
(n) :
Alternative form of Middle Earth: the Earth. [(archaic) The Earth.]
(n) :
(fiction) Alternative letter-case form of Middle-earth: the setting of the Lord of the Rings mythos. [(fiction) The main setting of J. R. R. Tolkien's Lord of the Rings and other works.]
(n) :
Alternative form of Middle Earth: (archaic) the Earth; (Norse mythology) Midgard. [(archaic) The Earth.]
(n) :
(fiction) Alternative letter-case form of Middle-earth. [(fiction) The main setting of J. R. R. Tolkien's Lord of the Rings and other works.]
(n) :
Alternative spelling of Middle Earth. [(archaic) The Earth.]