Etymology
editGothic aiþþau can't come from earlier *efþau, because Germanic -e- is only preserved in Gothic before -h-, -hw- or -r-; since *erþau would not be expected to assimilate, the preform must have been *ehþau or *ehwþau. Of the two, *ehþau matches expected Germanic *eh (< PIE *h₁eḱ(s)/*h₁eǵʰ(s)) in form, and even in meaning ("but/except/without (if/or)", cf. Celtic *extos, "except, but", Ancient Greek ἐκτός/ἐχθός, "without, outside" also "except"). Germanic *ehþau ("or, otherwise, but if") is then the source of Gothic aiþþau, Old English eþþa, Old Saxon ettho, Old Norse eða and probably Old High German edo, along with the initial element eddes-/edde-/ethe-/ette- in compounds like eddeslīh, "any, some".
The other Germanic forms seem to show initial elements in *uf- and *ef(i)-, along with conflation with *jab-. It seems as though Germanic *eh, *ef/*ifi and *uf (*ub) were used as disjunctive particles. Burgundaz (talk) 23:05, 15 August 2021 (UTC)