embitter

verb3

1. •
   (figurative) To cause (someone or their feelings) to become more angry, resentful, or unfriendly; to envenom.

   • Sometimes it [pride] stirreth vp men, and imboldeneth them to offer vvrongs: sometimes imbittereth men; and maketh them vvayvvard against the right: […] — 1608
2. •
   (figurative) To cause (a positive quality such as happiness, or a thing such as an activity or one's life) to become less good or pleasurable; also, to make (a negative quality, or thing such as a disagreement) worse or more unpleasant.

   • He imbitters not a distastfull message to a forrein Prince by his indiscretion in delivering it. — 1642
3. •
   (no longer used) To cause (something) to be or taste bitter; to bitter.