An adjective for “hollow” in The Etymologies of the 1930s under the root ᴹ√UNUK (Ety/UNUK).
Qenya
kulda
adjective. flame-coloured, golden-red
kulina
adjective. flame-coloured, golden-red
karne
adjective. red
unqa
adjective. hollow
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
An adjective in The Etymologies of the 1930s glossed “flame-coloured, golden-red” derived from the root ᴹ√KUL “golden-red” along with a variant ᴹQ. kulda (Ety/KUL), the latter probably derived from ✱kulnā. These adjectives replaced an early version kul(l)ina that seems to have only meant “red” (EtyAC/KUL).
Conceptual Development: The Qenya Lexicon and Poetic and Mythological Words of Eldarissa of the 1910s had ᴱQ. kuluvoite “golden” with variant kuluksa, an elaboration of ᴱQ. kulu “gold” under the early root ᴱ√KULU (QL/49; PME/49).