Early Quenya
okka
noun. knee
okkainen
cardinal. seventy
okkaiya
ordinal. seventeenth
otsokainen
cardinal. seventy
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
The word ᴱQ. okka “knee” appeared the Qenya Lexicon of the 1910s under the early root ᴱ√OQO “bend” (QL/70). The word appeared again in Early Qenya Word-lists of the 1920s (PE16/137).
Neo-Sindarin: I would retain ᴺQ. occa “knee” for purposes of Neo-Quenya as we have no better alternatives, though what its etymology would be in later conceptions of the language is unclear.