रास्

May be from an extension of Proto-Indo-European *Hrey- (“to cry, bellow”) as *Hrey-s- (compare Proto-West Germanic *rairōn, whence English roar), per a traditional model that allows the development of either Sanskrit ā or its pre-Indo-Iranian precursor *ē from PIE *ey, but this has largely fallen out of favor and may be coincidental. This etymology is incomplete. You can help Wiktionary by elaborating on the origins of this term. More likely from a root *HReH- or simply a late onomatopoeic formation.

• (Vedic) IPA^(key): /ɾɑːs/
• (Classical Sanskrit) IPA^(key): /ɾɑːs̪/

रास् • (rās)

1. to howl, cry

• रा (rā)

• Monier Williams (1899) “रास्”, in A Sanskrit–English Dictionary, […], new edition, Oxford: At the Clarendon Press, →OCLC, page 0879.
• Arthur Anthony Macdonell (1893) “रास्”, in A practical Sanskrit dictionary with transliteration, accentuation, and etymological analysis throughout, London: Oxford University Press
• William Dwight Whitney (1885) The Roots, Verb-forms, and Primary Derivatives of the Sanskrit Language, Leipzig: Breitkopf and Härtel, page 138

• Otto Böhtlingk, Richard Schmidt (1879-1928) “रास्”, in Walter Slaje, Jürgen Hanneder, Paul Molitor, Jörg Ritter, editors, Nachtragswörterbuch des Sanskrit [Dictionary of Sanskrit with supplements] (in German), Halle-Wittenberg: Martin-Luther-Universität, published 2016

• Pokorny, Julius (1959) “0859”, in Indogermanisches etymologisches Wörterbuch [Indo-European Etymological Dictionary] (in German), volume 3, Bern, München: Francke Verlag, page 0859