embitter

verb

1. (archaic, transitive)To cause (something) to be or taste bitter; to bitter.
2. (figuratively, transitive)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.”

   “The Proſpect of Death is ſo gloomy and diſmal, that if it vvere conſtantly before our Eyes, it vvould imbitter all the Svveets of Life.”

   “Their pleaſures, poor as they vvere, could not be preſerved pure, but vvere embittered by petty competitions and vvorthleſs emulation.”

   “A juſt, but melancholy reflection, embittered, hovvever, the nobleſt of human enjoyments.”

3. (figuratively, transitive)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; […]”

   “But tvvo things occaſioned great Contentions in them; The one vvas, the VVealth and Dignity of ſome Sees; the other vvas, the Heats that had been raiſed by the Arrian Hereſy, by vvhich Peoples minds vvere embittered one againſt another.”

   “She was at once humiliated and embittered; but the warm heart, and the strong mind, must have an object; and her energies, equally with her affections, had concentrated themselves on her son.”