Synonyms for Bitter:

adj.

angry (adjective)
huffy, irritable.
cold (adjective)
chilly, wintry, nippy, cold, ice-like, bitterly cold, frosty, frozen, icy, frigid, biting.
disappointing (adjective)
heartbreaking.
galling (adjective)
galling.
hateful (adjective)
malicious.
hostile, nasty (adjective)
hateful, resentful, intense, acrimonious, embittered, rancorous, sullen, antagonistic, vitriolic, sore, severe, caustic, biting, virulent, stinging.
ice-cold (adjective)
bitterly cold.
irritable (adjective)
caustic, irascible, churlish, irritable, cross, touchy, crabbed, crusty, cranky, petulant, prickly, peevish, spiteful, acerbic, acid, bellicose, huffy, surly, tart, acrimonious, bearish, snappish, sour, cantankerous, petty.
malevolent (adjective)
baleful, spiteful, vindictive, baneful, wicked, ill-natured, nasty, virulent, corrosive, antagonistic, foul, mean, Black-hearted, hurtful, malicious, hostile, evil, venomous, churlish, perfidious, sinister, malignant, sullen, rancorous, vicious, catty, malevolent, hateful, treacherous.
painful (adjective)
disagreeable, chafing, painful, acute, Irksome, inflaming, cruel, harrowing, troublesome, biting, grueling, galling, woeful, Cramping, burdensome, smarting, annoying, agonizing, arduous, odious, tormenting, grievous, stabbing, stinging, irritating, aggravating, anguishing, miserable, crushing, throbbing, insufferable, oppressive, piercing, trying, uncomfortable, unpleasant, excruciating, unbearable, Besetting, Gnawing, hurtful, offensive, Torturing., severe, aching, wrenching, horrendous, distressful, disturbing, withering, cutting, bothersome, sore.
painful, distressing (adjective)
distasteful, sharp, hard, unpalatable, offensive, annoying, unpleasant, galling, disturbing, brutal, grievous, heartbreaking, disagreeable, hurtful, poignant, woeful, cruel.
pungent (adjective)
spicy, acrid, tangy, caustic, piquant, sharp, pungent, sour, poignant.
pungent, sharp (adjective)
acerbic, acid, tart, sour, acerb, acrid.
resentful (adjective)
sore, stung, spiteful, envious, offended, acerbic, Spleenful, galled, malevolent, hurt, rancorous, irritated, infuriated, vexed, Piqued, Huffed, miffed, discontent, splenetic, antagonistic, vindictive, embittered, resentful.
severe (adjective)
severe.
sharp (adjective)
sharp.
sour (adjective)
pungent, acidic, sharp, unripe, acerb, sour, acerbic, tart, piquant.

n.

brackish, chocolate, chocolatey, flavored, bittersweet, fiery. angry, unfriendly, affective, deep-seated, burning, depth, basic, acutely, casual, cynical, deep, blind. adversary, taste, sworn, antagonist, Archenemy, deadly enemy/foe/rival, foe, nemesis, opponent, enemy, archrival. depressing, upsetting, comfort, tragic, heartbreaking, unhappy, dismal, brutal, rough, sad, terrible, hard. annoyed, mad, like, belligerent, put out, upset, distasteful, fed up, indigestible, displeased, unpalatable. ale, lager, keg, attitude, love, guest beer, brew, guinness, home brew, beer, brown ale. attribute (noun)
bitterness.
bitter (noun)
bitingly, painful, piercingly, unpleasant, vitriolic, hostile, bitterness, acerb, acid, blistering, biting, bitterly, sulfurous, sorrowful, caustic, acrid, resentful, sulphurous, virulent, intolerable, tasteful, acrimonious, acerbic, venomous.
cognition (noun)
bitterness.
intense (noun)
intense.
sarcastic (noun)
sarcastic.

v.

intensified (verb)
intense.

Other synonyms:

beer, ale, sad, brown ale, acutely, guinness, basic, affective, chocolatey, bittersweet, deep-seated, chocolate, guest beer, home brew, flavored, lager. keg, deep, brutal, blind, indigestible, distasteful, brew. casual. rough. hard. enraged
angry.
scornful
sarcastic.

Usage examples for bitter

  1. " I'm afraid you'll have to," she said with bitter decision. – The Literary Sense by E. Nesbit
  2. There could be but one thing more bitter that he or anybody else in the world should know it. – A Woman Named Smith by Marie Conway Oemler
  3. Freeman is a bitter man to go against, but I'm not afraid to try him out. – Shawn of Skarrow by James Tandy Ellis