*agiþō

From Proto-Indo-European *Hokét-(y)eh₂-, traditionally analyzed as *h₂oḱ-ét-eh₂ from the o-grade form *h₂oḱ- of root *h₂eḱ- (Kroonen et al. 2022: 8; Mallory & Adams 1997: 434–35). The Proto-Germanic form is usually reconstructed as *agiþō-, but the alternative *ageþjō- has been proposed because it would correspond especially well to Baltic *akētiā-, reflected in Old Prussian aketes and Lithuanian akė́čios, dialectal ekė́čios (Kroonen et al. 2022: 8; van Sluis et al. 2023: 236), though Mallory and Adams (1997: 434–35) consider the Baltic changes secondary. Cognates include Old Welsh ocet, Latin occa, and Ossetic адæг (adæg), though the Ossetic form may be a later loan rather than an inherited Indo-Iranian cognate (Koch 2020: 134; Kroonen et al. 2022: 8).