Synonyms for Hard:

adj.

adverse (adjective)
grievous, adverse, opposing, burdensome, calamitous, tragic, detrimental, woeful, troublesome, catastrophic, inauspicious, untoward, unlucky, perilous, difficult, unfavorable, unfriendly, disastrous, miserable, antipathetic, unfortunate, distressful, unpropitious.
bony (adjective)
ossified.
certain (adjective)
inarguable, incontestable, undisputable.
depressing (adjective)
bleak.
difficult (adjective)
onerous, arduous, tricky, rough, demanding, bothersome, knotty, burdensome, difficult, wearisome, formidable, oppressive, severe, wearing, uphill, contrary, cantankerous, trying, stressful, tough, harsh, thorny, stiff, tight, finicky, fussy, troublesome, cumbersome, complicated, strenuous, rugged, complex, grinding, toilsome, ticklish, adverse, wearying, laborious.
effortful (adjective)
effortful.
flinty (adjective)
steely.
hard (adjective)
solid, rigid, stiff, callous, firm.
insensitive (adjective)
hardened, nonchalant, emotionless, ruthless, apathetic, passive, hard-boiled, unemotional, unsympathetic, cool, unfeeling, numb, objective, cold-blooded, insensitive, unconcerned, blunt, indifferent, hardhearted, stony, passionless, tough, detached, callous, heartless, aloof, anesthetized, uncompassionate, dispassionate.
intoxicating (adjective)
alcoholic.
obstinate (adjective)
obstinate.
positive (adjective)
positive.
resentful (adjective)
rancorous.
rocklike (adjective)
callous, unyielding, rocky, tough, stony, dense, hardened, set, thick, strong, solid, adamantine, stiff, packed, firm, rigid.
rocky (adjective)
petrous, rocklike, stonelike.
severe (adjective)
exacting, grim, severe.
solid (adjective)
set, firm, concrete, unyielding, substantial, stable, dense, solid, physical.
tenacious (adjective)
indefatigable, persistent, persevering, bulldogged, stubborn, determined, obdurate, true, courageous, insistent, strong-willed, steadfast, flintlike, tough, resolute, devoted, enduring, hearty, indomitable, bold, faithful, stony, decisive, fervent, staunch, undaunted, unflagging, diligent, obstinate, dogged, plucky, dauntless, strong, bullheaded, brave, stiff, tenacious, headstrong, spunky, tireless.
true, indisputable (adjective)
practical, definite, positive, sure, undeniable, pragmatic, realistic, down-to-earth.

adv.

all (adverb)
firmly.
in a fixed manner (adverb)
tight, firmly.
with determination (adverb)
strenuously.
with difficulty (adverb)
laboriously, carefully.
with great force (adverb)
heavily, severely, vigorously.

n.

authentic, definite, definitely. evil, monstrous, hateful, active. fearless, audacious, daring, strenuously, vigorously, heroic, laboriously, carefully. FULL BORE, concerted, as if your life depends on it, by the sweat of your brow, painstaking, resist, all-out, flat out, incompressible, last-ditch. hardy, hard-bitten, be an effort, Hard-handed, continue. frost, icy, icicle, black ice, sharp, taxing, exacting, effortful, glare ice, exigent, ice over. dour, bleak, hot, grim, attitude. comfort, bitter. stonyhearted, Cold-hearted, compassionless. rancorous, virulent, love, embittered, acrimonious, resentful. incontrovertible, sure, certain, undeniable, positive, irrefutable, undisputable, inarguable, indubitable, unquestionable, indisputable, incontestable. real, factual. practical, sober, down-to-earth, tough-minded, realistic, prosaic, unromantic, excite, pragmatical, matter of fact, pragmatic, hardheaded. ingestion, spirituous, intoxicative. alcoholic (noun)
stimulating, intoxicating.
compact (noun)
unyielding, thick.
cruel (noun)
perverse, unrelenting, vengeful.

Other synonyms:

pragmatic, acrimonious, prosaic, frosty, saline, undeniable, disagreeable, indisputable, strenuously, powerful, packed, irrefutable, frost, dour, incompressible, vigorously, realistic, down-to-earth, factual, incontrovertible, exacting, embittered. hardheaded, unquestionable, evil, practical, moist, hardy, exigent, matter of fact, grim. taxing, virulent, sober, bitter, hefty, wet, bleak. positive, crisp. awful. cold. certain. sharp. Other relevant words:
hardheaded, hefty, cruel, spirituous, rigorous, stonyhearted, grim, unrelenting, hard-bitten, hardy, callous, alcoholic, heavy, unyielding, dour.

Usage examples for hard

  1. Had he perhaps been too hard – Quicksands by Adolph Streckfuss
  2. Too hard upon him! – The Comedies of Terence by Publius Terentius Afer
  3. " I-" " So hard is it? – The Henchman by Mark Lee Luther