Simple past tense and past participle of imbitter.(verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "imbittered" in a sentence
"The pride of ancestry, which rankled in the bosom of the ancient gentry, was more openly expressed by their ladies, and was, moreover, imbittered not a little by the political feuds of the time, for most of the Southern chiefs were friends to the authority of the Queen, and very jealous of the power of Murray."
"He became the object of those affectionate feelings, which, finding formerly no object on which to expand themselves, had increased the gloom of the castle, and imbittered the solitude of its mistress."
"Two circumstances only had imbittered their union, which was otherwise as happy as mutual affection could render it."