Gnomish
mem
noun. mouth
gogail
noun. mouth
gogel
noun. mouth
gogìl
noun. mouth
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. gogel “mouth” in The Gnomish Grammar (GG/8) and as {gogel >} gogíl or gogail “mouth” in the Gnomish Lexicon of the 1910s (GL/40). In the latter document, Tolkien said it was a combination of G. go- “together” and G. cail “lip”, from more archaic forms gwa-caíl, gwa-cil. An unrelated word G. mem “mouth” also appeared in Gnomish Lexicon (GL/57), perhaps related to G. beg “chin” which Tolkien connected to ᴱQ. pé “(closed) mouth” = “the two lips” (GL/57; QL/72).
Neo-Sindarin: I’ve used these Gnomish words as the inspiration for a neologism ᴺS. gobem “mouth”, based on the (neologism) ᴺS. pemp “lip”, where the reduction of -mp to -m finally is an irregular assimilation to the preceding voiced b: -mp > -mb > -m.