An Etymological Dictionary of the German Language/Annotated/seufzen
seufzen, verb, ‘to sigh, lament,’ from the equivalent Middle High German siufzen, siuften; the z of the Middle High German form is due to the influence of the intensives in -zen; in Old High German sûftôn, sûfteôn, ‘to sigh,’ allied to Middle High German sûft, ‘sigh.’ The latter is an abstract from Old High German sûfan, ‘to drink’; hence seufzen, literally ‘drawing in the breath’; it is related to saufen, as schluchzen is to schlucken. Note, however, English to sob, Middle English sobbin, Anglo-Saxon *sobbian, ‘to sob, sigh,’ which may be allied to Old High German sûfteôn.