Eä

Eä is the Quenyan name for the universe, the Created World brought into realization by Eru Ilúvatar and the Ainur during the Music the Valar, in the beginning of time and creation. Eä was formed from the Flame Imperishable of Ilúvatar, sustainable and separate from the Void. The Valar were to become part of the new realm never to leave until The End.

The extent and size of Eä was said to be beyond the thoughts of Elves or Men, and the only known world of this universe, the dwelling-place of Ilúvatar's children, was Arda, also home to the Blessed Realm of Valinor, as well as the lands of Middle-earth.

https://tolkiengateway.net/wiki/Eä