What is "numenor"

Númenor , also called Elenna-nórë or Westernesse, is a fictional place in J. R. R. Tolkien's writings. It was a huge island located in the Sundering Seas to the west of Middle-earth, the main setting of Tolkien's writings, and was known to be the greatest realm of Men. However, the inhabitants' cessation of the service to Eru Ilúvatar and rebellion against the Valar led to the downfall of the island and death of the majority of its population.

The author had intended Númenor to be an allusion to the legendary Atlantis. An unfinished story Aldarion and Erendis is set in the realm of Númenor at the time of its zenith, and Akallabêth summarizes its history and downfall. Otherwise only compendious or abandoned writings of Tolkien deal with Númenor, such as the appendices to The Lord of the Rings and several accounts published in Unfinished Tales and The History of Middle-earth series.

Originally intended to be a part of a time-travel story, the tale of the fall of Númenor was for some time viewed by Tolkien as a conclusion to his Silmarillion and the "Last Tale" about the Elder Days. Later, with the emergence of The Lord of the Rings, it became the link between these two works and a major part of his legendarium.