staunen.

Attested since the 17th century, then introduced in the general written language by Albrecht von Haller (1708-1777), from Alemannic German stūnen, of uncertain origin. Probably related to stauen (“to dam, retain”). Alternatively—though less likely both on semantic and phonetic grounds—from Old French estoner, whence English astound, astonish. Probably not related to English stun (German stöhnen). The original sense is “to become stiff, stand still”, used especially of the eyes and thus “to muse, contemplate, romanticise” (German sinnen, schwärmen, schwelgen), which is the sense in which Haller used it. Outside of Switzerland, however, the word was reinterpreted by backformation from the derivative erstaunen (“to amaze, astonish”), which had already been in general use since the 16th century.