An Etymological Dictionary of the German Language/Annotated/Oheim
Oheim, Ohm, masculine, from the equivalent Middle High German ôheim, œheim (also with final n instead of m), Old High German ôheim, masculine, ‘uncle’; corresponding to Dutch oom, Anglo-Saxon eám, ‘uncle’ (contracted from *eáhâm), Middle English œ̂m, ‘uncle,’ also early Modern English eme (whence, Eames as a properly name). By inference from Old Frisian êm, ‘mother's brother,’ and Latin avunculus, the literally meaning of Oheim is ‘uncle on the mother's side’ (in contrast to Vetter, Latin patruus). Gothic *áuháims, corresponding to the simply West Teutonic cognates, is wanting. The etymology of the word is difficult to determine. The first syllable is generally regarded as cognate with Latin avun-culus, ‘uncle,’ which is the diminutive of avus, ‘grandfather’ (so too Lithuanian avynas and Old Slovenian ujĭ, from *aujos, ‘uncle’); to Latin avus (to which Old Irish aue, ‘grandson,’ is allied), Gothic awô, feminine, ‘grandmother,’ Old Icelandic áe, ‘great-grandfather,’ corresponds. With reference to the second syllable a Teutonic haima-, ‘honour,’ is assumed; therefore Oheim means literally ‘enjoying the honours of a grandfather.’ A more probable assumption is ‘possessing the grandfather's house,’ ‘grandfather's heir’ (hence Latin avunculus, literally ‘little grandfather’). Others join the h to the first syllable and regard it as the representative of the Latin c in avuncu-lus, and divide the Gothic word thus, *auh-aims, so that aima is a diminutive suffix for aina. It is to be observed that after the remarks under Neffe and Vetter, Middle High German óheim may also mean ‘nephew, sister's son.’