An Etymological Dictionary of the German Language/Annotated/Ei
Ei, masculine, ‘egg,’ from Middle High German and Old High German eì, neuter, ‘egg’; common to Teutonic with the same meaning, although Gothic *addjis, neuter (compare Old Icelandic egg), is wanting; ada, however, is found in Crimean Gothic. Compare Old Saxon ei, Dutch ei, Anglo-Saxon œ̂g, neuter English egg is borrowed from Scandinavian egg. Between the Teutonic aias (ajjas), neuter, ‘egg,’ and the corresponding terms in the West Aryan languages there is an unmistakable agreement of sound, although the phonetic justification for the comparison has not yet been found; compare Latin óvum (Low Latin *ŏvum, on account of French œuf), Greek ὠόν, Old Slovenian jaje, aje (from the base *êjo-?), Old Irish og, ‘egg.’ Arguing from these cognates, Teutonic ajjas, neuter, has been derived from êwjo-, ôwjo-, and connected with Latin avis, Sanscrit vi, ‘bird.’ In East Aryan no corresponding word is found.