Quenya 

Ambarenya

middle-earth

Ambarenya, older [MET] Ambarendya place-name "Middle-earth" (but the more usual word is Endor, Endórë) (MBAR)

Endamar

middle-earth

Endamar place-name "Middle-earth" (EN, MBAR, NDOR). However, Middle-earth is normally called Endor, Endórë.

Endor

middle-earth

Endor place-name "Middle-earth" (SA:dôr, NDOR), "centre of the world" (EN); also long form Endórë "Middle-earth" (Appendix E); allative Endorenna "to Middle-earth" in EO. The form Endór in MR:121 may be seen as archaic, intermediate between Endórë and Endor (since long vowels in a final syllable are normally shortened: Endór > Endor). Endór functions as an uninflected genitive in the source: Aran Endór, "King of Middle-earth".

endor

noun. Middle-earth

Quenya [PE 22:125; 126] Group: Mellonath Daeron. Published by

Sindarin 

ennor

middle-earth

Ennor, also in coll. pl. ennorath = lands of Middle-earth (RGEO, Letters:384). Apparently less usual is the term Emerain.