Wurdahuzdą: Proto-Germanic dictionary — *efþau Scott K. Shay Wardja Press https://protogermanic.org/pgmc_efþau

Single-entry extract from the dictionary. Cross-references to other entries point to their identifiers in the full dictionary.

 *h₁eǵʰs/*h₁eḱ
efþau ˈeɸ.θɑu̯ ᛖᚠᚦᚨᚢ
conjunction or From *eh (‘but, except’, from Proto-Indo-European *h₁eǵʰs/*h₁eḱ (s), ‘out’) + *þau (‘in that case’, from PIE *tó-we, from PIE *to-, ‘this, that’ + *-we, ‘or’). The first element *eh is debated: many accounts assume *ef- matching West Proto-Germanic f-variants (e.g. Old English ofþe, Old Saxon eftha), possibly influenced by the Proto-Germanic conditional particle family (‘if’); however, Gothic aiþþau is often taken to point to an earlier *ehþau with subsequent assimilation producing *-þþ-. The second element *þau is less controversial, though there are many other competing theories on its PIE heritage.
Old English eþþa, ofþe, oððe, oðþe, oþðe, oþþa, oþþe, oþþon Middle English oththe, other, or English or
Scots or
Old Frisian ieftha, ioftha, jef, jof, jova, ofte Saterland Frisian af, of
West Frisian of
Old Saxon efdo, eftha, eftho, ettho Middle Low German edder, odder
Old Saxon efdo, eftha, eftho, ettho Middle Low German efte, afte, ufte, uft, uf Low German of Sauerland Low German of, o'
Old Dutch *oftho, *ofto Middle Dutch ofte, ochte Dutch ofte, of Afrikaans ofte, of
Old High German odo Middle High German:
Old High German odo Old High German odar, odor Middle High German od, ode, oder German oder
Luxembourgish oder
Yiddish אָדער (oder)
Old Norse eða, eðr Icelandic eða, eður
Old Danish æthæ, eth
Old Gutnish eþa
Gothic 𐌰𐌹𐌸𐌸𐌰𐌿 (aiþþau)