A word for “metal” in The Etymologies of the 1930s under the root ᴹ√TINKŌ of the same meaning (Ety/TINKŌ).
Conceptual Development: A possible precursor is G. sinc “metal” from the Gnomish Lexicon (GL/67), a cognate of ᴱQ. sink “mineral, gem, metal” under the early root ᴱ√SINI “pale blue” in the contemporaneous Qenya Lexicon (QL/83). For purposes of Neo-Sindarin, I prefer to use ᴺS. sinc for “✱mineral”.
A word appearing as N. rhaudh “hollow, cavernous” in The Etymologies of the 1930s, derived from ᴹ✶rōda [rǭda] based on the root ᴹ√ROD “cave” (Ety/ROD).
Neo-Sindarin: Many Neo-Sindarin writers adapt this adjective as ᴺS. raudh “hollow, cavernous” for purposes of Neo-Sindarin as suggested in HSD (HSD), since the unvoicing of initial r to rh was a feature of Noldorin of the 1930s but not Sindarin of the 1950s and 60s.
Conceptual Development: The Gnomish Lexicon of the 1910s had G. rothrin “hollow” based on G. †roth “cave, grot” (GL/65). It also had G. rûdin “hollow, cavernous” based on G. †rûda, an archaic form of grûd(a) “cavern” (GL/42, 66).