ᴹ√ROK root. “run on foot”
This root was the basis for Elvish “horse” words starting in the 1930s. It first appeared as unglossed ᴹ√ROK in The Etymologies of the 1930s with the derivatives ᴹQ. rokko/N. roch “horse” (Ety/ROK). The root was given the gloss “run on foot” in a page of roots from the Quenya Verbal System of the 1940s, but that page was rejected. Primitive ✶rokkō “horse” was mentioned regularly in Tolkien’s later writing (Let/282; PE21/82; WJ/407), though in one place he clarified that it was more specifically a “swift horse for riding” (Let/382).
References ✧ Ety/ROK; EtyAC/LOP; PE22/127