IPA: /ˈbɪtərnəs/
KK: /ˈbɪtərnəs/
The state or quality of being unpleasantly sharp or harsh in taste or feeling, often associated with strong feelings of anger or resentment.
After the argument, there was a lingering bitterness between them.
Bitterness → It is formed from "bitter" (from Old English "biter", meaning having a sharp taste or unpleasant flavor) and "-ness" (meaning the state or quality of). The word "bitterness" refers to the state of having a sharp, unpleasant taste or feeling.
Think of the word 'bitter' to remember that 'bitterness' describes the quality of having a sharp, unpleasant taste or feeling.