Gnomish
ilbrant
noun. rainbow
ilbranteloth
place name. Ilbranteloth
ilvrant
noun. rainbow
cris ilbranteloth
place name. Gully of the Rainbow Roof
cris a teld quing ilon
place name. Gully of the Rainbow Roof
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.