An Etymological Dictionary of the German Language/Pflaume
Pflaume, f., from the equiv. MidHG. pflûme, f., ‘plum’; borrowed, as the permutated initial pf from p indicates, previous to the OHG. period (see Pfirsich) from Lat. prûnum, ‘plum,’ or rather its plur. prûna. The change of gender in names of fruit was made even in the Rom. group, as is shown by the words corresponding to Lat. cerasum, pomum, morum, and pirum; see Birne and Kirsche. Hence the late OHG. pfrûma, f., ‘plum,’ in closer connection with the Lat. form, and also pflûmo, ‘plum-tree.’ The s of the Lat. word is changed into l, as in Lat. morus, equiv. to Maulbeerbaum (comp. also Pilgrim, from Lat. peregrînus, which has, besides, m for Lat. n). Numerous MidHG. and ModHG. dial. forms, as well as the corresponding Du. pruim, likewise contain r; comp., on the other hand, AS. plûme, E. plum. The Rom. derivatives of Lat. prûnum are Fr. prune, Ital. prugna, Span. pruna (in MidLat. too forms with l and m occur instead of r and n; m, moreover, appears in South-East Fr. dials.). As to the time when the word was borrowed, see Pfirsich.