An Etymological Dictionary of the German Language/Apfel
Apfel, n., ‘apple,’ from the equiv. MidHG. apfel, OHG. apful (also afful, plur. epfili), m.; a word common to the Teut. group, by chance not recorded in Goth. Comp. Du. and LG. appel, m., AS. œppel, m. (in the plur. neut.), E. apple, OIc. eple, n., ‘apple’ (Goth. *aplus, m.?). The apple-tree in West Teut. is *apuldr, f.; comp. OHG. affoltra, AS. apuldr, which are preserved in the local names ModHG. Affoltern, Affaltrach, (Apolda?), Du. Apeldoren, E. Appledore. In spite of this diffusion throughout the entire Teut. group, and of the mention of wild apple-trees in Tacitus, the whole class must be recognised as loan-words (Obst has no connection whatever with them). They must, however, have been borrowed long before the beginning of our era, since the Teut. p in apla- has, in accordance with the permutation of consonants, originated in a prehistoric b; comp. Ir. aball, uball, Lith. obůlys, OSlov. alŭko, ‘apple.’ As nothing testifies to the Aryan origin of these oblu- cognates (in Lat. mâlum- Gr. μῆλον), found only in the North of Europe, we must assume that the word was borrowed. The derivation from Lat. malum Abellanum (the Campanian town Abella was famed in antiquity for its apples), is on phonetic and formal grounds doubtful, although in the abstract (comp. Pfirsich) the combination is interesting. No other explanation of how it was borrowed has yet been found. It is noteworthy that for Augapfel, ‘pupil,’ apful alone (as well as ougapful) can be used in OHG.; comp. AS. œppel, n. (plur., also masc.), E. apple of the eye (also eyeball), Du. oogappel; but, on the other hand, OIc. augasteinn.