A neologism for “to scratch” created by Boris Shapiro and Petri Tikka in PPQ (PPQ) from the early 2000s, based on the root ᴹ√SRIP. I would use attested [ᴱQ.] nyas- “to scratch” instead.
Primitive elvish
rip
root. *strip, stripe, rim
ris
root. cut, cleave, cut; [ᴹ√] slash, rip; cleave
kiris
root. cleave, cleave, [ᴹ√] cut, [ᴱ√] split
This root first appeared as ᴹ√RIS “slash, rip” in The Etymologies of the 1930s with the derivative N. risto “rend, rip” (Ety/RIS¹). Tolkien then created a new entry for ᴹ√RIS without deleting the prior entry, with derivatives like ᴹQ. rista/N. rhest “a cut” and ᴹQ. rista-/N. rhista- “cut” (Ety/RIS²); this seems to reflect a conceptual shift of “slash, rip” >> “cut”. Indeed, the root √RIS reappeared in Tolkien’s later writings with the gloss “cut” (PE17/87). Christopher Tolkien gave this root the gloss “cleave” in the Silmarillion Appendix (SA/ris).