disastrous
1. [ adjective ] (of events) having extremely unfortunate or dire consequences; bringing ruin
Synonyms: black fateful fatal calamitous
Examples:

"the stock market crashed on Black Friday" "a calamitous defeat" "a disastrous end to a disastrous campaign" "this would be absolutely fatal to my theory"

Related terms: unfortunate
Similar spelling:   disastrously
  disaster
  digester
  digestion
  die-cast