An Etymological Dictionary of the German Language/beschwichtigen
beschwichtigen, vb., ‘to appease, compose.’ The Germans connect this word instinctively with schweigen; it forced its way, however, in the last half of the preceding cent. from LG. into the written language, and its cht is the earlier HG. ft; it corresponds to MidHG. swiften, ‘to pacify,’ OHG. swiftôn, ‘to be quiet.’ The stem is the same as in Goth. sweiban, ‘to cease, leave off’; with this the cognates of schweigen accord fairly well both in sound and meaning; the Teut. root swī̆b, swī̆g, is based upon the Aryan swī̆q (swī̆g in Gr. σϊγάω; see under schweigen).