Gnomish
gwelaith
noun. boil, bubble
gweleth
noun. boil, bubble
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.
gwelaith
noun. boil, bubble
gweleth
noun. boil, bubble
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. gwelaith or gweleth in the Gnomish Lexicon of the 1910s with the gloss “(a) boil, a bubble”, a noun form of G. gwel- “to boil, bubble” (GL/44).
Neo-Sindarin: Since I retain ᴺS. gwel- “to boil, bubble” for purposes of Neo-Sindarin, I would retain ᴺS. gweleth “boil, bubble” as well.