Gnomish
lingos
noun. snake
fenlug
noun. snake
fent
noun. snake
lûg
noun. snake
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 for “snake” in the Gnomish Lexicon of the 1910s, along with a deleted variant fenlug (fenlog-) (GL/34), the latter probably a combination with G. lûg “snake”. It was clearly a cognate of ᴱQ. fent “serpent” from the contemporaneous Qenya Lexicon (QL/38).