An Etymological Dictionary of the German Language/Neffe
Neffe, m. (with abnormal ff), ‘nephew,’ from MidHG. nëve, OHG. něvo, m.; orig. existing in all the OTeut. dials. (now obsolete in Suab. and Bav.). The meaning in the older languages was not so definite as at present; MidHG. nëve, most frequently means ‘sister's son,’ also more rarely ‘brother's son,’ likewise ‘uncle,’ then generally ‘relative’; Du. neef, ‘grandson, nephew, cousin,’ AS. nëfa, ‘grandson, nephew’ (E. nephew is based on Fr. neveu), OIc. nefe, m., ‘relative.’ Goth. *nifa, m., is by chance not recorded. The cognates are primitive and common to the Aryan group; Teut. *nefôd, nom. sing. (of which there is a fem. form niftî; see Nichte), from pre-Teut. népôt, appears in Ind. nápât (stem náptṛ), ‘descendant, son, grandson,’ Lat. nepos, ‘grandson,’ Gr. ἀνεψιός, ‘first cousin,’ νέποδες, ‘brood,’ OIr. nia, ‘sister’s son.’ With regard to the fluctuation of meaning see Braut, Oheim, Vetter, and Schwager.