Early Quenya
tanka
noun. fastening, rivet
tanka
adjective. firm, fixed, fast; steady, (stead)fast
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 noun appearing as ᴱQ. tanka “fastening, rivet” in the Qenya Lexicon of the 1910s written under the adjective ᴱQ. tanka “firm, fixed, fast, steady”, both based on the early root ᴱ√TAKA “fix, fasten” (QL/88).
Neo-Quenya: The root √TAK and adjective tanca survive in Tolkien’s later writing, so I think the noun ᴺQ. tanca “fastening, rivet” can also be retained for purposes of Neo-Quenya, perhaps as a nominalized form of the adjective.