Synonyms for Stiff:

adj.

dead (adjective)
inert.
difficult (adjective)
arduous, tough, laborious, difficult, hard, uphill.
extreme, severe (adjective)
steep, unconscionable, exact.
formal, standoffish (adjective)
mannered, headstrong, cold, forced, unnatural, inflexible, pertinacious, strong, ungainly, stilted, stubborn, artificial, obstinate.
hard (adjective)
firm, hard, rigid, callous, solid.
hard, inflexible (adjective)
inelastic, ungraceful, thick, tight, taut, firm, petrified, rigid, solid, wooden, frozen, unyielding, hardened, benumbed, stony, indurate, buckram, starchy, tense.
inelastic (adjective)
unalterable, unyielding, firm, inflexible, rigid, immovable, inelastic.
pretentious (adjective)
forced, studied, overdone, unnatural, mannered, fraudulent, stagy, imitation, counterfeit, posing, synthetic, la-di-da, pretentious, stilted, facade, showy, false, Impersonating, affected, mock, histrionic, Masquerading, theatrical, ostentatious, fake, ersatz, bogus, imposture, deceitful, forged, artificial.
rocklike (adjective)
hard.
severe (adjective)
exact.
sky-high (adjective)
sky-high.
tenacious (adjective)
headstrong, determined, flintlike, indomitable, hard, obstinate, bold, obdurate, devoted, stubborn, diligent, stony, faithful, brave, strong, dauntless, enduring, bullheaded, true, tireless, indefatigable, unflagging, bulldogged, courageous, tenacious, insistent, persistent, plucky, persevering, undaunted, strong-willed, steadfast, dogged, decisive, hearty, resolute, fervent, staunch, tough, spunky.
unskillful (adjective)
awkward.

n.

agonizing, burning, agonising, chronic, achy, crippling, angry, bad, acute, chapped. grave, profound, serious, dire, tighten, awful, desperate. purpose, unflinching, gouge, shortchange, bleed, peddle your influence, soak, underpay, constant, whack. concentrated, the departed, the dead, body count, the deceased. rock-hard, steep, sky-high, big, stratospheric, impenetrable, usual, unconscionable, packed. corpse (noun)
carcass, carrion, body, decedent, mummy, cadaver, remains, corpse.
dead body (noun)
carcass, corpse, cadaver.
formal (noun)
ungainly, ungraceful, awkward.
stiff (noun)
inebriated, blind drunk, immobile, pie-eyed, cadaver, clay, potty, squiffy, rigid, uphill, smashed, stand up, besotted, wet, hard, pixilated, inflexible, tight, starchy, soused, blotto, slopped, loaded, intoxicated, soaked, fuddled, crocked, stiffly, sloshed, tiddly, corpse, tipsy, formal, plastered, sozzled, buckram, strong, tiddley, remains.
unfriendly (noun)
unpleasant, distant, cold, aloof, unfriendly, antagonistic, icy, hostile, churlish.

Other synonyms:

hardened, motionless, body count, underpay, stratospheric, difficult, rock-hard, stationary. wooden, sedentary, packed, cold, unflinching, gouge, soak, sky-high, impenetrable. static, steep. inert, unconscionable, concentrated. constant, whack. still. formal
formal.
stand-up
stand up.
Other relevant words:
buckram, cold, formal, blotto, steep, arduous, awkward.

Usage examples for stiff

  1. It's a very stiff birth, the nurse told me. – Ulysses by James Joyce
  2. Mr. Lavender, pale and stiff was sitting in his study, with Blink on his feet, reading a speech. – The Burning Spear by John Galsworthy
  3. Though my leg is stiff my arms are not, as Sweyn shall learn if I meet him. – The Dragon and the Raven or, The Days of King Alfred by G. A. Henty