embitter

verb

Etymology: From em- (variant of the suffix en- with the sense ‘to become’) + bitter.

1. To cause (something) to be or taste bitter; to bitter.
2. 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.”

   “[I]t is our fond conceits, our froward humors, our perverse behaviors, which do create the trouble, which seemeth adherent to any condition, and embittereth every state; which from any slight occasion doth create vexation, and turneth every event into disaster.”

3. 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: […]”

   “And hovv farre the like cenſurings and deſpiſings have embittered the ſpirits, and vvhetted both the tongues and pens of learned men one againſt another in our ovvne Church; […]”