A noun appearing as G. gwem “worm” in the Gnomish Lexicon of the 1910s (GL/45), probably derived from the early root ᴱ√GWEVE that was the basis for “worm” words in the contemporaneous Qenya Lexicon (QL/103).
Neo-Sindarin: I think this word is worth retaining as (archaic?) ᴺS. gwem “worm” for purposes of Neo-Sindarin as a derivative of the Neo-Root ᴺ√WEB, though I expect the 1964 word S. leweg “worm” is more commonly used.
A verb appearing as G. tertha- or tercha- “devour, destroy” in the Gnomish Lexicon, perhaps related to G. terch “worm” [= “✱worm eaten”] (GL/70) and thus ultimately derived from the early root ᴱ√TEŘE “pierce, boring” (PME/91).
Neo-Sindarin: Since √TER “pierce” survives in Tolkien’s later writings, I would retain ᴺS. tertha- “destroy” for purposes of Neo-Sindarin, originally with the sense “✱fill with holes”, but for “devour” I would use ᴺS. ammad-.