Gnomish
cas
noun. head, skull
corob
noun. skull
nôl
noun. head
ontha
pronoun. his
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!
A word appearing as G. corob “a skull” in the Gnomish Lexicon of the 1910s (GL/26), likely related to ᴱ√KORO “be round” (QL/48).
Neo-Sindarin: Since √KOR “round” survived in Tolkien’s later conception of the languages, I’d retain this word as ᴺS. corob “skull”, especially since other early “skull” words such as ᴱN. cas derived from ᴱ√KASA “head” were probably no longer viable since non-initial s generally vanished in Sindarin.