What names were used for the otherworld in Irish tradition?

In Irish tradition, the otherworld was envisioned as a realm free from sickness, aging, and death, where happiness was eternal. It was referred to by several names, including:1

• The Land of the Living1
• Delightful Plain1
• Land of the Young1

Additionally, the otherworld was often associated with the sídh (or sidhe), which refers to the hills or mounds—often perceived as underground forts or palaces—where the fairy folk were believed to reside.23

While these regions represented a blissful existence for the fortunate, Irish cosmology also included Tech Duinn, the domain of the god Donn, which served as the destination for the souls of the dead.1