A word appearing as G. drô “wheel track, rut” in the Gnomish Lexicon related to G. norn “wheel” and derived from the early root ᴱ√nor- (GL/31); the root was glossed “run, go smoothly, ride, spin, etc.” in the contemporaneous Qenya Lexicon (QL/67). As for G. drô, Tolkien initially glossed it as “(same)” indicating it had the same meaning as the entry G. dronn “race, course, track” above it, but this gloss was deleted and replaced by “wheel track, rut”.

Neo-Sindarin: The root √NOR was associated with both “run” and “roll” as late as 1948 (PE22/127), so I would retain ᴺS. drô “wheel track, rut” for purposes of Neo-Sindarin. For a similar development, compare N. draug “wolf” < ᴹ✶d’rāk based on ᴹ√DARAK (Ety/DARÁK), but in the case of *n’ro there is the additional sound change of initial nr- becoming dr-.