Bitter
Part of speech: noun
Definition: (usually in the plural bitters) A liquid or powder, made from bitter herbs, used in mixed drinks or as a tonic. A type of beer heavily flavored with hops.
Part of speech: adjective
Definition: Having an acrid taste (usually from a basic substance) Harsh, piercing or stinging Hateful or hostile Cynical and resentful
Example sentence: It's not surprising, then, they get bitter, they cling to guns or religion or antipathy to people who aren't like them or anti-immigrant sentiment or anti-trade sentiment as a way to explain their frustrations.
Acrimonious
Part of speech: adjective
Definition: Of words, arguments, quarrels: bitter; mean-spirited; sharp in language or tone.