*aunaz

From Proto-Indo-European *h₂egʷ-nó-s, probably via pre-Germanic *akʷna-. The Germanic *auna- would regularly suggest PIE *gʷʰ (de Vaan 2008: 30), but Ancient Greek ἀμνός (amnós) and Old Church Slavonic агнѧ (agnę), the latter showing Winter’s-law lengthening (Derksen 2008: 26–27, s.v. *àgnьcь), favor plain *gʷ. The Germanic form is therefore best explained as early remodeling of *akʷna- under the influence of *awiz, before Kluge’s Law (Stiles 2018: 249–252). Cognate with Proto-Italic *agʷnos, whence Latin agnus (de Vaan 2008: 30), and Proto-Celtic *ognos, whose unexpected *o- may likewise reflect influence from *owis (Matasović 2009a: 301–302). The PIE noun has no secure deeper etymology.