bitterness

Concise Oxford English Dictionary © 2008 Oxford University Press:
bitter/ˈbɪtə(r)/

▶adjective

• 1 having a sharp, pungent taste or smell; not sweet.

• 2 causing pain or unhappiness.

  ■ feeling or showing angry hurt or resentment.

  ■ (of a conflict) harsh and acrimonious.

• 3 (of wind or weather) intensely cold.

▶noun

• 1 Brit. beer that is strongly flavoured with hops and has a bitter taste.

• 2 (bitters) [treated as sing.] alcohol flavoured with bitter plant extracts, used as an additive in cocktails.

– phrases
to the bitter end to the very end, in spite of difficulties.

– derivatives
bitterly adverb,
bitterness noun.

– origin OE biter, of Gmc origin.