Númenor [‘noo-meh-nor] – a large star-shaped island between Middle-earth and Valinor; created and given as a gift to the faithful Men (Edain) after Morgoth was overthrown; destroyed as punishment for the audacity of the Númenoreans; ancient home of the royal lines of Gondor and Arnor; the island offered everything more beautiful than in Middle-earth except forests and wood (hence the mass destruction of Middle-earth forests for the Númenorean fleets).
Also called: Anadûnë, Westernesse
You know if from: the island and its fall are mentioned several times in LotR; in Gondor it’s a custom to look westwards towards “Númenor that was” before meals (TTT).

Meneltarma [meh-nehl-‘tahr-mah] (“The Pillar of Heaven”) – a lone mountain in the middle of Númenor; on its top there was a shrine of Eru Ilúvatar.

Andúnië [ahn-‘doo-nee-eh] – city and haven on the western coast of Númenor; the lords of this region were the ancestors of the kings of Gondor and Arnor, the last one being Elendil.

Armenelos [ahr-‘meh-neh-loss] – royal city in central Númenor; dwelling place of the king.