A root in The Etymologies of the 1930s glossed “rush, fly, fling” with derivatives like ᴹQ. rimpa “rushing, flying” and N. rhib- “to flow like a (?torrent)”, the latter an element in the name N. Rhimdath “Rushdown” (Ety/RIP). This river name appeared in early maps from Lord of the Rings drafts from the 1940s (RS/205), but the river was unlabeled in the published version of The Lord of the Rings. As for the root ᴹ√RIP, it reappeared with the gloss “fling, hurl (of something long like an arrow, spear, shaft)” in a rejected list of roots from Quenya Verbal System of the 1940s, having a single derivative in the past form ᴹQ. rimpe “hurled” (PE22/127 note #141). In this list ᴹ√RIP appeared immediately above the root ᴹ√KHAT “hurl”, which also appeared in The Etymologies of the 1930s (Ety/KHAT).

Neo-Eldarin: For purposes of Neo-Eldarin, I think it is better to use the better-known root ᴹ√KHAT for “hurl, fling”, which derivatives like Q. hatal “spear” as late as the 1960s. If ᴹ√RIP is used, it is probably best to give it the meaning of its derivatives from The Etymologies: “rush, fly”.