An Etymological Dictionary of the German Language/räuspern
räuspern, vb., ‘to hawk, clear the throat,’ from the equiv. MidHG. riuspern (riustern). This verb, which is not recorded prior to MidHG., belongs to a root frequently occurring in Teut., rū̆k (Aryan rū̆g), ‘to belch, eructate,’ the k disappearing before the suffix sp, st; comp. AS. roccettan, ‘to belch,’ OHG. itarucchen, MidHG. itrücken, AS. edorcan (eodorcan), ‘to chew the cud.’ Comp. Lat. ê-rûgere, ‘to spit out,’ rûminare (for *rûgminare), ‘to chew the cud,’ and ructare, ‘to belch,’ Gr. ἐρεύγεν, ‘to spit out,’ ἐρυγή, f., ‘vomiting,’ OSlov. rygati sę ‘to belch,’ Lith. atrūgas, f. pl., ‘rising of the stomach.’