An Etymological Dictionary of the German Language/Annotated/Schwäre
Schwäre, feminine, ‘ulcer, boil, sore,’ from Middle High German swër, Old High German swëro, masculine, ‘physical pain, disease, swelling, ulcer’; allied to Middle High German swërn, Old High German swëran, ‘to hurt, pain, fester, ulcerate.’ The root swer originally perhaps ‘to press, torment’; compare the Sanscrit root svṛ, ‘to torment, injure.’ See schwer and Geschwür.