(bit′ər) adjective
1. Having a peculiar acrid taste, as quinine.
2. Producing pain of body or mind; keen; poignant; severe.
3. Feeling or showing hate or resentment.
4. Stinging; sharp; severe: said of words.
—noun
1. That which is bitter; bitterness.
2. plural A bitter vegetable tonic, usually spirituous.
3. Brit. Bitter beer.
—v.t. & v.i. To make or become bitter. [OE biter <bītan bite]
—bit′ter·ish adjective
—bit′ter·ly adverb
—bit′ter·ness noun Synonyms (adj.): acerb, acetous, acid, acidulated, acidulous, acrid, acrimonious, biting, caustic, cutting, harsh, irate, pungent, savage, sharp, sour, stinging, tart, vinegarish, virulent. Acid, sour, and bitter agree in being contrasted with sweet, but acid or sour applies to the taste of vinegar or lemon juice; bitter to that of quassia, quinine, or strychnine. Acrid is nearly allied to bitter. Pungent suggests the effect of pepper or snuff on the organs of taste or smell; as, a pungent odor. Caustic indicates the corroding effect of some strong chemical, as nitrate of silver. In a figurative sense we say a sour face, sharp words, bitter complaints, caustic wit, cutting irony, biting sarcasm, a stinging taunt, harsh judgment, a tart reply. Harsh carries the idea of intentional and severe unkindness, bitter of a severity that arises from real or supposed ill-treatment. Tart and sharp utterances may proceed merely from a wit recklessly keen; cutting, stinging, or biting speech indicates more or less of hostile intent. The caustic utterance is meant to burn. Compare MALICIOUS, MOROSE. Antonyms: dulcet, honeyed, luscious, nectared, saccharine, sweet.

(bit′ər) noun Naut.
A turn of the cable round a mooring bitt. [<BITT]