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.
singwa
adjective. salt
singwe
noun. salt
singe
noun. salt
A noun appearing as ᴱQ. {singi >>} singe “salt” in the Qenya Lexicon of the 1910s and under the early root ᴱ√SIŊI (QL/83). The contemporaneous Poetic and Mythological Words of Eldarissa had ᴱQ. singi “salt” (PME/83). Early Qenya Word-lists of the 1920s had ᴱQ. singwe “salt” (PE16/145).
Neo-Sindarin: Of these various forms, I’d use ᴺQ. singë for “salt” for best compatibility with [G.] sing “salt”, but would assume its stem form is singi- and that it was a derivative of the Neo-Root ᴺ√SIÑGI.
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 appearing as ᴱQ. singwa “salt (aj.)” in the Qenya Lexicon of the 1910s, an adjective form of ᴱQ. singe “salt” (QL/83).
Neo-Quenya: I’d retain ᴺQ. singwa “salt[y]” for purposes of Neo-Quenya.