A phrase demonstrating the use of the genitive prefix an-, elided to ’n in this case (SD/435). Earlier in the same discussion, Tolkien gave the non-elided (but less common) variant: thâni anAmân. It may be contrasted with the genitive compound Amatthâni in which the adjective element Amân appears first.
Adûnaic
thâni
noun. land
thâni’namân
Land of Aman
A noun translated “land” (SD/435) appearing in the Adûnaic names for the Blessed Realm: Amatthâni and thâni’nAmân. Its Primitive Adûnaic form was also ✶thāni, though its primitive was glossed “realm" (SD/420).