Synonyms for Calamitous:

adj.

adverse (adjective)
distressful, unlucky, inauspicious, unfriendly, catastrophic, difficult, hard, miserable, unpropitious, antipathetic, disastrous, unfavorable, troublesome, detrimental, grievous, tragic, woeful, untoward, opposing, unfortunate, burdensome, perilous, adverse.
all (adjective)
black, fatal, fateful, disastrous.
baneful (adjective)
cursed, baneful, infectious, wicked, cancerous, poisonous, contagious, ill, evil.
destructive (adjective)
devastating, ruinous, injurious, deadly, catastrophic, deleterious, damaging, cataclysmic, harmful, detrimental, disastrous, cataclysmal, destructive.
direful (adjective)
inauspicious, unpropitious.
disastrous; tragic (adjective)
deadly, adverse, catastrophic, unfortunate, grievous, fatal, harmful, ruinous, cataclysmic, woeful, devastating, unfavorable.
evil (adjective)
detrimental, evil, nefarious, disgraceful, monstrous, atrocious, repugnant, sinful, baneful, offensive, destructive, reprehensible, loathsome, abominable, bad, foul, repellent, heinous, wicked, terrible, revolting, hideous, damnable, repulsive, sinister.
harmful (adjective)
risky.
ruinous (adjective)
ruinous.

n.

dangerous, risky, unsafe, hazardous. cataclysmal, help, ruinous, cataclysmic. calamitous (noun)
disastrous, fatal, black, unfortunate, fateful.
disastrous (noun)
ruinous.

Other synonyms:

cataclysmal, cataclysmic. Other relevant words:
dangerous, black, risky, hazardous, ruinous, help, fatal, unsafe, fateful, cataclysmic, cataclysmal.

Usage examples for calamitous

  1. Forty days after this calamitous event, the tyrant Ricimer died of a painful disease, and two months later death also removed Olybrius. – The World's Greatest Books, Vol XI. by Edited by Arthur Mee and J.A. Hammerton
  2. Amongst the calamitous record there were four more of the name- their bodies scattered widely in distant unknown graves, victims of the spirit of adventure and unrest. – The Shadow of the East by E. M. Hull
  3. It was to be sublime, but insane and calamitous nevertheless. – The Life and Works of Friedrich Schiller by Calvin Thomas