Katzenjammer \KAT-suhn-jam-er\ , noun;
1. The discomfort and illness experienced as the afteraffects of excessive drinking; hangover
2. Uneasiness; anguish; distress
3. Uproar; clamor
This word is attested to 1849 as "a hangover," but since it is colloquial American English it is probably much older. It comes from German katze ("cat") + jammer ("distress, wailing"), so the later sense of "any unpleasant reaction" (1897) makes sense.
Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Friday, January 7
Etymologies come from the Oxford English Dictionary and/or Etymonline.com