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.
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.