Bitter

Adjective

 * 1) Having an acrid taste (usually from a basic substance)
 * 2) Harsh, piercing or stinging
 * 3) Hateful or hostile
 * 4) Cynical and resentful

Noun

 * 1)  A liquid or powder, made from bitter herbs, used in mixed drinks or as a tonic.
 * 2) A type of beer heavily flavored with hops.
 * 3)  A turn of a cable about the bitts.

Adverbs for Bitter
maliciously; shrewdly; enviously; viciously; purposely; unnecessarily;  uncontrollably;insidiously; invidiously; sharply; cynically; sarcastically; spitefully; jealously; intentionally; cunningly; ironically; insinuatingly; incisively; cruelly; brutally; unwisely; atrociously; malevolently; tauntingly; caustically; diabolically.

Synonyms for Bitter
acrid, sour, disagreeable, distasteful, sharp, biting.

Antonyms for Bitter
sweet, pleasant, agreeable.

Thesaurus
acerb, acerbate, acerbic, acid, acidic, acidulent, acidulous, acrid, acrimonious, affecting, afflictive, aftertaste, algid, alienated, amaroidal, annoying, antagonistic, antipathetic, arctic, asperous, astringent, austere, bad, belligerent, below zero, bilious, biting, bitter as gall, bitterly cold, bleak, boreal, brisk, brumal, brutal, burning, caustic, cheerless, choleric, clashing, coarse, cold, cold as charity, cold as death, cold as ice, cold as marble, colliding, comfortless, conflicting, corroding, corrosive, crisp, cruel, cutting, deplorable, depressing, depressive, despiteful, disagreeable, discomforting, dislikable, dismal, dismaying, dispiriting, displeasing, distasteful, distressful, distressing, disturbing, divided, dolorific, dolorogenic, dolorous, double-edged, dreary, dyspeptic, edged, embittered, escharotic, estranged, fierce, flavor, freezing, freezing cold, frigid, full of hate, galling, gelid, glacial, grievous, gust, hard, harsh, hateful, hibernal, hiemal, hostile, hyperborean, ice-cold, ice-encrusted, icelike, icy, incisive, inclement, intemperate, irreconcilable, irritating, jaundiced, joyless, keen, lamentable, malevolent, malicious, malignant, miserable, mordacious, mordant, mournful, moving, nasty, nipping, nippy, nose-tickling, numbing, obnoxious, offensive, painful, palate, pathetic, penetrating, piercing, pinching, piquant, piteous, pitiable, poignant, provoking, pungent, quarrelsome, rancorous, rankled, raw, regrettable, relish, reproachful, repugnant, resentful, resenting, rigorous, rough, rueful, rugged, sad, saddening, salt, sapidity, sapor, savor, savoriness, scathing, scorching, set against, severe, sharp, sleety, slushy, smack, snappy, sore, sorrowful, sour, sour-tempered, soured, spiteful, splenetic, stabbing, stewing, stinging, stomach, stone-cold, strident, stringent, subzero, supercooled, sweet, tang, tart, taste, thankless, tongue, tooth, touching, trenchant, ugly, unalluring, unappealing, unappetizing, unattractive, uncomfortable, undelectable, undelicious, undesirable, unengaging, unenjoyable, uninviting, unkind, unlikable, unpalatable, unpleasant, unpleasing, unsavory, untasteful, unwelcome, vehement, venomous, vexatious, vicious, vinegarish, violent, virulent, vitriolic, winterbound, winterlike, wintery, wintry, withering, woebegone, woeful, wretched

Etymology
bitter

Derived terms

 * bitter pill to swallow
 * brought up to a bitter