Gnomish
cûn
adjective. bowed, bent, concave
cû
noun. bow, crescent; the waxing or waning moon
cunwed
adjective. bowed, bent, concave
cuvon
adjective. bowed, bent, concave
nil
adjective. empty
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.
A word in the Gnomish Lexicon of the 1910s with related verb G. nilta- or niltha- “to empty (tr.)”, but no other obvious cognates from this period (GL/60).