Qenya
anka
noun. jaw, row of teeth
nangwa
noun. jaw
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 for “jaw” The Etymologies of the 1930s derived from primitive ᴹ✶nakma under the root ᴹ√NAK “bite” (Ety/NAK). It was possibly displaced by anca “jaw, jaws”, which was also introduced in The Etymologies of the 1930s, but continued to appear in later documents included The Lord of the Rings Appendix E (LotR/1123). However, it might be that nangwa refers to a single “jaw” (upper or lower), while anca refers collectively to both “jaws”.