An Etymological Dictionary of the German Language/Annotated/Pfennig
Pfennig, masculine, ‘a coin, one-tenth of a penny,’ from Middle High German pfęnnic, pfęnninc (genitive -ges), Old High German pfęnning, masculine, ‘denarius, a silver coin, a twelfth of a shilling.’ Its form and origin are difficult to determine. It may be derived from Pfanne, and thus its name may be due to its shape (perhaps ‘pan-shaped’ or ‘made in the pan’). A variant with nd, from the connection of the word with Pfand, is seen in Old High German pfęnting and Anglo-Saxon pęnding (variants of the more usual pęnning, pęnnig, whence English penny). With regard to the diffusion of the word, compare further Old Saxon pending, Dutch penning, Old Icelandic penningr; in Gothic a presumptive form *panniggs or *pandiggs is wanting. The suffix -ing frequently occurs in names of coins in the earlier periods; compare Schilling, Silberling, Old High German cheisuring, ‘imperial gold coin,’ English farthing, from Anglo-Saxon feórþing, ‘quadrans.’ From the Teutonic cognates are derived Old Slovenian pěnęgŭ, pěnędžĭ, ‘coin, money.’