Early Noldorin
cas
noun. skull, skull, [G.] head
nod
noun. head
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 appearing as G. cas “head, skull” in the Gnomish Lexicon of the 1910s, where Tolkien said it was “only used of physical head of bodies” (GL/25). It was clearly derived from the early root ᴱ√KASA “head” (QL/31). The word ᴱN. cas “skull” reappeared in Early Noldorin Word-lists of the 1920s (PE13/140). Given the tendency of non-initial s to vanish in later iterations of the language (something that was not a feature of Gnomish of the 1910s), Tolkien likely abandoned this word.