The Adûnaic name for Númenor (Q. Númenórë), with the same meaning as its Quenya name: “Westernesse” (S/261). In The Silmarillion appendix, Christopher Tolkien stated that is it a loan word from Elvish (SA/andúnë). According to J.R.R. Tolkien’s own writing (SD/426), this is true, albeit not directly. Anadûnê is a feminized form of the adjective anadûni “western, of the west”, which is itself related to S. dûn “west”.
Quenya
númenórë
place name. Westernesse, (lit.) West-land
The island-continent where the Edain settled after the fall of Beleriand (LotR/1035, S/261), often appearing in its shorter form Númenor. It is generally translated as “Westernesse” (LotR/194, S/261) but more literally means “West-land” (Let/224, RC/778). It is a compound of númen “west” and nórë “land” (Let/361).
Conceptual Development: In the very first draft of the Fall of Númenor, this name was given as ᴹQ. Númar or ᴹQ. Númenos (LR/11), but in the next draft these became the name its capital city, and the name Númenor emerged as the name of the land (LR/14). The full form ᴹQ. Númenóre appeared in The Etymologies, already with the derivation discussed above (Ety/NDŪ). It also appeared in an adjectival form Númenórea in linguistic notes from the 1930s (PE22/19).