A noun in the Qenya Lexicon of the 1910s gloss “joint” under the early root ᴱ√LEQE (QL/53).
Early Quenya
oksa
noun. joint
leqet
noun. joint
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.
The word ᴱQ. oksa “joint” appeared in the Qenya Lexicon of the 1910s under the early root ᴱ√OSO whose other derivative was ᴱQ. oswe “hip” (QL/71).
Neo-Quenya: I’d retain the word ᴺQ. oxa “joint” for purposes of Neo-Quenya, but would not derive it from √OS any longer. I would assume it is derived from a Neo-Root ᴺ√OTH, a variant of ᴹ√OS “round” perhaps originally referring to the round joint. Compare Q. ruxa < RUTH + kā (PE17/188).