वज्

• उज् (uj), ओज् (oj)

From a merger of:

• Proto-Indo-Iranian *waȷ́-, from Proto-Indo-European *weǵ- (“fresh, strong”). Compare Latin vegeō (“excite, arouse; be lively”) whence English vegetation; Latin vigeō (“thrive, be alive”) whence vigil, vigor; English wake, watch.
• Proto-Indo-Iranian *Hawǰ-, from Proto-Indo-European *h₂ewg- (“to increase”). Compare Latin augeō and English augment.

• (Vedic) IPA^(key): /ʋɐd͡ʑ/
• (Classical Sanskrit) IPA^(key): /ʋɐd͡ʑ/

वज् • (vaj)

1. to be hard or strong

• Monier Williams (1899), “वज्”, in A Sanskrit–English Dictionary, […], new edition, Oxford: At the Clarendon Press, →OCLC, page 0913.
• William Dwight Whitney (1885), The Roots, Verb-forms, and Primary Derivatives of the Sanskrit Language, Leipzig: Breitkopf and Härtel, page 152

• Otto Böhtlingk; Richard Schmidt (1879-1928), “वज्”, 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
• Monier Williams (1899), “वज्”, in A Sanskrit–English Dictionary, […], new edition, Oxford: At the Clarendon Press, →OCLC, page 235.
• Mayrhofer, Manfred (1992), Etymologisches Wörterbuch des Altindoarischen [Etymological Dictionary of Old Indo-Aryan]‎^[1] (in German), volume 1, Heidelberg: Carl Winter Universitätsverlag, page 278
• Mallory, J. P. with Adams, D. Q. (2006), The Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World (Oxford Linguistics), New York: Oxford University Press, →ISBN, page 372
• Rix, Helmut, editor (2001), Lexikon der indogermanischen Verben [Lexicon of Indo-European Verbs] (in German), 2nd edition, Wiesbaden: Dr. Ludwig Reichert Verlag, →ISBN, page 662
• Pokorny, Julius (1959), Indogermanisches etymologisches Wörterbuch [Indo-European Etymological Dictionary] (in German), volume IV, Bern, München: Francke Verlag, page 1117