Synonyms for Difficult:

adj.

adverse (adjective)
unfortunate, hard, distressful, antipathetic, detrimental, burdensome, tragic, unlucky, adverse, inauspicious, calamitous, unfriendly, perilous, opposing, troublesome, catastrophic, grievous, disastrous, miserable, woeful, untoward, unfavorable, unpropitious.
all (adjective)
hard.
ambitious (adjective)
severe, strenuous.
complex (adjective)
mysterious, puzzling, complex, intricate, convoluted, perplexing, involved, obscure, abstruse, complicated.
crotchety (adjective)
fractious, obstinate.
dangerous (adjective)
hairy.
difficult (adjective)
cumbersome, bothersome, demanding, severe, wearing, finicky, laborious, harsh, stiff, grinding, adverse, complex, tight, uphill, wearying, tough, complicated, toilsome, hard, strenuous, formidable, rough, stressful, troublesome, fussy, thorny, wearisome, onerous, rugged, contrary, tricky, burdensome, cantankerous, arduous, knotty, trying, oppressive, ticklish.
effortful (adjective)
effortful.
hard on someone; hard to do (adjective)
bothersome, arduous, trying, tough, labored, gargantuan, strenuous, burdensome, troublesome, formidable, demanding, immense, wearisome, unyielding, exacting, stiff, intricate, problematic, toilsome, uphill, ambitious, onerous, effortful, challenging, severe, laborious, titanic, painful, herculean.
mean (adjective)
ornery.
unintelligible (adjective)
incomprehensible.
unmanageable socially (adjective)
irritable, fussy, perverse, finicky, fractious.

n.

moody, short-tempered, temperamental, hot-tempered, bad-tempered, perverse, irritable, irascible, careful. inopportune, unbecoming, unseemly, improper, inappropriate, unsuited, untimely, unsuitable. effortful, weighty, exigent. comfort, inconvenient, incommodious. contrarious, froward, impossible, attitude, balky, support, wayward, ornery. difficult (noun)
ticklish, troublesome, tall, embarrassing, arduous, vexed, sticky, knotty, baffling, fractious, trying, problematic, catchy, tricky, thorny, hard-fought, nasty, problematical, tough, tight, unenviable, ambitious, awkward, rough, serious, rugged, stubborn, rocky, herculean, hard, delicate, challenging.

Other synonyms:

enigmatic, fraught, unfathomable, tangled, contentious, ornery, unclear, invidious, unaccountable, effortful, contrarious, disruptive. confused, contorted, froward, ambiguous, balky, incommodious, wayward, impossible. rigorous, inconvenient, weighty, elaborate. perverse. bad. abstruse
abstract.
arcane
esoteric.
circuitous
labyrinthine.
demanding
exacting, exigent.
forced
labored.
incomprehensible
inscrutable.
mystical
metaphysical.
puzzling
confusing.
troublesome
taxing.
unexplainable
inexplicable.

Usage examples for difficult

  1. This is not a difficult matter. – Amusements in Mathematics by Henry Ernest Dudeney
  2. Only the particular answer he found difficult to speak. – The Truants by A. E. W. (Alfred Edward Woodley) Mason