There is no compelling etymology for Greek ὕβρις (hubris) ‘wanton violence’. Earlier attempts to relate this word to the Indo-European root *gwerh2- 'heavy' are unsatisfactory, as they do not explain the inflection in short -ĭ-; moreover, a preposition ὑ- is not supported by any actual evidence. A different solution can be offered: some Homeric usages of ὕβρις suggests that the original meaning of this word may have been simply ‘physical power’. This paper argues that ὕβρις goes back directly to PIE acrostatically inflected i-stem abstract noun *Hi̯o(H2)gw-ri- ‘might’, internally derived from *Hi̯aH2gw-ro- ‘mighty’ (the root of ἥβη, lith. (pa)-jėgà), with the loss of laryngeal according to the Weather-rule and change of ο to υ in labial environment (Cowgill’s Law).