bitter

adjective

• 1having a sharp, pungent taste or smell; not sweet:the raw berries have an intensely bitter flavor
• (of chocolate) dark and unsweetened.

• 2(of people or their feelings or behavior) angry, hurt, or resentful because of one’s bad experiences or a sense of unjust treatment:I don’t feel jealous or bitter
• (of a conflict, argument, or opponent) full of anger and acrimony:a bitter, five-year legal battle

• 3(often used for emphasis) painful or unpleasant to accept or contemplate:today’s decision has come as a bitter blow

• 4(of wind, cold, or weather) intensely cold:a bitter wind blowing from the east

noun

• 1British beer that is strongly flavored with hops and has a bitter taste.

• 2 (bitters) [treated as singular] liquor that is flavored with the sharp pungent taste of plant extracts and is used as an additive in cocktails or as a medicinal substance to promote appetite or digestion.