Early Quenya
mandos
place name. Hell
mandor
place name. Hell
fatanyu
place name. Hell
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.
Qenya name for G. Inthanfog “Hell” (GL/51). In might be a compound of Fâ “Lowest Air” and some form of tan(y)a “fire”, since its Gnomish equivalent contains G. Tanfa “hot air of the deep places”.