bitterness
/ˈbɪtənəs/noun
The sharp, harsh quality of a bitter flavor.
More often describes lingering resentment than flavor: bitterness over a lost promotion can last years.
Related words
hostilityUnfriendly or aggressive feelings or behavior toward someone.resentmentA lasting feeling of anger or bitterness about being treated unfairly.contemptA feeling that someone or something is worthless or beneath respect; scorn.outrageA strong feeling of shock and anger caused by something unfair or offensive.disgustA strong feeling of dislike or revulsion toward something unpleasant or offensive.rageExtreme, uncontrolled anger.