bitter

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Having or being a taste that is sharp, acrid, and unpleasant.
• adjective Causing a sharply unpleasant, painful, or stinging sensation; harsh.
• adjective Difficult or distasteful to accept, admit, or bear.
• adjective Proceeding from or exhibiting strong animosity.
• adjective Resulting from or expressive of severe grief, anguish, or disappointment.
• adjective Marked by resentment or cynicism.
• adverb In an intense or harsh way; bitterly.
• transitive verb To make bitter.
• noun That which is bitter.
• noun A bitter, usually alcoholic liquid made with herbs or roots and used in cocktails or as a tonic.
• noun Chiefly British A sharp-tasting beer made with hops.

from The Century Dictionary.

• To make bitter; give a bitter taste to; embitter.
• noun Nautical, a turn of a cable round the bitts.
• noun An old form of bittern.
• Having a harsh taste, like that of wormwood or quinine.
• Hence Unpalatable; hard to swallow, literally or figuratively: as, a bitter pill; a bitter lesson.
• Hard to be borne; grievous; distressful; calamitous: as, a bitter moment; bitter fate.
• Causing pain or smart to the sense of feeling; piercing: painful; biting: as, bitter cold; “the bitter blast,”
• Harsh, as words; reproachful; sarcastic; cutting; sharp: as,“bitter taunts,”
• Cherishing or exhibiting animosity, hate, anger, or severity; cruel; severe; harsh; stern: as, “bitterest enmity,” Shak., Cor., iv. 4; “bitter enemies,”
• Evincing or betokening intense pain or suffering: as, a bitter cry.
• noun That which is bitter; bitterness.
• noun Specifically A bitter medicine, as a bitter bark or root, or an infusion made from it. See bitters.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Naut.) AA turn of the cable which is round the bitts.
• noun that part of a cable which is abaft the bitts, and so within board, when the ship rides at anchor.
• transitive verb To make bitter.
• noun Any substance that is bitter. See bitters.
• adjective Having a peculiar, acrid, biting taste, like that of wormwood or an infusion of hops.
• adjective Causing pain or smart; piercing; painful; sharp; severe.
• adjective Causing, or fitted to cause, pain or distress to the mind; calamitous; poignant.
• adjective Characterized by sharpness, severity, or cruelty; harsh; stern; virulent.
• adjective Mournful; sad; distressing; painful; pitiable.
• adjective (Bot.) See Colocynth.
• adjective (Bot.) a plant of the genus Cardamine, esp. Cardamine amara.
• adjective (Min.) tale earth; calcined magnesia.
• adjective (Chem.) a class of substances, extracted from vegetable products, having strong bitter taste but with no sharply defined chemical characteristics.
• adjective Epsom salts; magnesium sulphate.
• adjective (Bot.) a name given to two European leguminous herbs, Vicia Orobus and Ervum Ervilia.
• adjective to the last extremity, however calamitous.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Having an acrid taste (usually from a basic substance)
• adjective Harsh, piercing or stinging
• adjective Hateful or hostile
• adjective Cynical and resentful
• noun A liquid or powder, made from bitter herbs, used in mixed drinks or as a tonic.
• noun A type of beer heavily flavored with hops.
• noun nautical A turn of a cable about the bitts.
• verb To make bitter.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the property of having a harsh unpleasant taste