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.
pinqe
adjective. slender, thin
san rotser simpetalla pinqe
*then pipes playing their thin music
sild(r)a
adjective. slender
An adjective in the Qenya Lexicon of the 1910s appearing as silda or sildra “slender”, derived from the early root ᴱ√SḶŘḶ [ÞḶÐḶ] (QL/73).
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 in the Qenya Lexicon of the 1910s glossed “slender, thin” derived from the early root ᴱ√PIKI or ᴱ√PINI (QL/73).