Synonyms for Adverse:

adj.

adverse (adjective)
antipathetic, calamitous, opposing, miserable, tragic, disastrous, grievous, hard, inauspicious, burdensome, unfortunate, unfavorable, unfriendly, untoward, unpropitious, unlucky, woeful, perilous, distressful, detrimental, difficult, troublesome, catastrophic.
all (adjective)
contrary, inauspicious, untoward.
at variance (adjective)
opposing.
difficult (adjective)
cumbersome, hard, wearing, grinding, harsh, rough, complex, severe, tight, formidable, onerous, tricky, trying, thorny, complicated, bothersome, uphill, cantankerous, demanding, stressful, wearisome, finicky, knotty, strenuous, wearying, oppressive, fussy, laborious, difficult, arduous, troublesome, rugged, ticklish, tough, burdensome, contrary, toilsome.
harmful (adjective)
risky.
opposing (adjective)
oppositional, adversarial.
unfavorable, antagonistic (adjective)
inopportune, disadvantageous, unfortunate, inimical, opposing, opposed, contrary, unfriendly, unlucky, detrimental, unpropitious, negative, conflicting.

n.

hazardous, ruinous, unsafe, risky. disruptive, support, oppositional, problematic, contentious, adversarial, invidious, embarrassing, opposed, antagonistic, fraught. unadvantageous, disadvantageous, negative, unsatisfactory, help. adverse (noun)
harmful, contrary, unfavorable, unfavourable, untoward, inauspicious.
hostile (noun)
antagonistic, conflicting, inimical.
unfavorable (noun)
inopportune, disadvantageous.

Other synonyms:

disadvantageous, negative, invidious, adversarial, problematic, contentious, fraught, oppositional, unadvantageous, disruptive. antagonistic, embarrassing, opposed. unsatisfactory. antagonistic
inimical.
clashing
conflicting.
Other relevant words:
disruptive, contentious, invidious, harmful, unadvantageous, antagonistic, inopportune, unsafe, risky, hazardous, fraught, adversarial, embarrassing, disadvantageous, inimical, unfavourable, conflicting, help, negative, support, problematic, ruinous, oppositional, unsatisfactory, opposed.

Usage examples for adverse

  1. Alas for the adverse fate of Susan Meynell! – Charlotte's Inheritance by M. E. Braddon
  2. The sloop, under the direction of Newton, had continued her course for two days against the adverse yet light breeze, when the weather changed. – Newton Forster by Frederick Marryat
  3. The more pleased the other side, the more reason to fear that matters were adverse on ours. – The Passenger from Calais by Arthur Griffiths