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.
uivrin
adjective. barren
gwivrin
adjective. barren
uith
adjective. both
A word for “both” in the Gnomish Lexicon of the 1910s related to G. gwi- “twi-, bi-, di-”. It had variants uith, uivren, and athwi, but all these were deleted (GL/20, 74).
athwi
adjective. both
ilgiol
adjective. barren
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.
An adjective appearing as G. uivrin “barren” in the Gnomish Lexicon of the 1910s glossed, the negated form of G. ivrin “fertile” (GL/46, 74). It had a variant form G. gwivrin “barren” where with the “ui- being replaced by analogy” (GL/46).
Neo-Sindarin: I would update this word to ᴺS. aliavren “barren” for purposes of Neo-Sindarin, based on the updated word ᴺS. iavren “fertile”.