A noun for “bark” in the Gnomish Lexicon of the 1910s (GL/63), apparently based on the early root ᴱ√PARA [PAÐA?] which might mean “peel” (QL/72).
Gnomish
dafros
noun. bark, skin, peel
dâf
noun. bark
padhwen
noun. bark
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 in the Gnomish Lexicon of the 1910s glossed “bark, skin, peel”, related to the verb G. daf- “strip, flay, peel skin” (GL/29). In Gnomish Lexicon Slips modifying that document, Tolkien instead gave {daus >>} dâf “bark” (PE13/112).