An Etymological Dictionary of the German Language/Annotated/Pein

by Friedrich Kluge

Pein, feminine, from the equivalent Middle High German pîne, pîn, Old High German pîna, feminine, ‘pain, punishment, torture’; adopted during the Old High German period on the introduction of Christianity from Latin poena, which was pronounced pêna in Middle Latin (compare Italian pena); Middle Latin ê appears in High German as î in other cases also (see Kreide and Feier), Compare Old Saxon pîna, Dutch pijn, Anglo-Saxon pîn, English pine (a later variant of pain); also Old Irish pían (genitive péne).