Gnomish
tereg
noun. worm
gwem
noun. worm
terch
noun. worm
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 G. gwem “worm” in the Gnomish Lexicon of the 1910s (GL/45), probably derived from the early root ᴱ√GWEVE that was the basis for “worm” words in the contemporaneous Qenya Lexicon (QL/103).
Neo-Sindarin: I think this word is worth retaining as (archaic?) ᴺS. gwem “worm” for purposes of Neo-Sindarin as a derivative of the Neo-Root ᴺ√WEB, though I expect the 1964 word S. leweg “worm” is more commonly used.