Gnomish
tarn
noun. gate
tarn fui
proper name. Door of Night
muil
noun. tarn
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 word appearing in the Gnomish Lexicon glossed “tarn” (GL/58). Its etymology is unclear. In later writings, muil had a number of different meanings.