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!
Gnomish
sinc
noun.metal
A noun from the Gnomish Lexicon of the 1910s appearing as G. sinc “metal” (GL/67), clearly the cognate of ᴱQ. sink “mineral, gem, metal” from the root ᴱ√SINI (QL/83).
Neo-Sindarin: I would retain this word for purposes of Neo-Sindarin, but would revise its sense to ᴺS. sinc “mineral”, derived from the primitive form ✶sinki (PE17/108) which may itself mean “✱mineral”; see that entry for discussion. I would use N. tinc for “metal”.
A noun from the Gnomish Lexicon of the 1910s appearing as G. sinc “metal” (GL/67), clearly the cognate of ᴱQ. sink “mineral, gem, metal” from the root ᴱ√SINI (QL/83).
Neo-Sindarin: I would retain this word for purposes of Neo-Sindarin, but would revise its sense to ᴺS. sinc “mineral”, derived from the primitive form ✶sinki (PE17/108) which may itself mean “✱mineral”; see that entry for discussion. I would use N. tinc for “metal”.