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".
Quenya
aran endór
proper name. King of Middle-earth
Changes
Aran Endór→ Tarumbar “King of Middle-earth” ✧ MR/121
Endor
middle-earth
endor
noun. Middle-earth
Endamar
middle-earth
Endamar place-name "Middle-earth" (EN, MBAR, NDOR). However, Middle-earth is normally called Endor, Endórë.
Ambarenya
middle-earth
Ambarenya, older [MET] Ambarendya place-name "Middle-earth" (but the more usual word is Endor, Endórë) (MBAR)
A (rejected) title of Morgoth, replaced by the more grandious title Tarumbar “King of the World” (MR/121). This name is a compound of aran “king” and Endórë “Middle-earth”, though for some reason the final -ë was omitted (perhaps a slip).