In the Etymologies, the second element in Helkarakse is said to be the Quenya word karakse ("jagged hedge of spikes"). Helge Fauskanger has suggested that the first element (hel-) derives from the root KHELEK ("ice"). Also in the Etymologies, Tolkien experimented with Noldorin translations of Hekarakse: elcharaes, helcharaes or Helcharach.
Quenya
helcaraxë
place name. Grinding Ice
helcaraxë
Helcaraxë
The ice-filled strait between Araman and Middle-earth (S/80). Its name was translated in a speech by Angrod (S/129): “Wherefore should we that endured the Grinding Ice bear the name of kinslayers and traitors?” It is a compound of helca “icy, ice-cold” (SA/helca) and caraxë “jagged hedge of spikes” (Ety/KARAK).
Conceptual Development: This name first appeared as ᴱQ. Helkarakse in the earliest Lost Tales, though at this early stage it was glossed “Icefang” (LT1/167), and Christopher Tolkien suggested its second element might be aksa “waterfall” (LT1A/Helkaraksë). In Silmarillion drafts from the 1930s, the translation of ᴹQ. Helkarakse was changed to “Grinding Ice” (SM/95, LR/125). The name also appeared in this form in The Etymologies (Ety/KARAK), where the derivation noted above is found. It was changed to Helcaraxë (Helkaraxë) in Silmarillion revisions from the 1950s-60s after Tolkien changed the orthographic representation of Quenya to be more like Latin (MR/194).