Adunakhor was born in the year II 2709, at the time when his great-grandfather Tar-Alcarin held the Sceptre of Numenor. When Adunakhor was twenty-eight years old, his grandfather Tar-Calmacil succeeded as King. Until that time it had been tradition for the Kings of Numenor to take their names in the Elvish form, but Tar-Calmacil became the first to use a name in his native Adunaic. Though he officially used the Elvish name Tar-Calmacil, privately Calmacil was known by the name Ar-Belzagar.
When Adunakhor succeeded in turn to become Numenor's twentieth ruler, he took his rejection of the Elvish tongues to an extreme degree. Not only did he publicly take a name in his native tongue - Ar-Adunakhor ("Lord of the West") - but he even went so far as to ban the use of Elvish languages from use in his kingdom. It was thus during his reign that Elves no longer travelled openly to the land of Numenor, but came only secretly to its western shores, where still many of the Faithful were friendly to them.