Adjective fatal has 4 senses
  1. fatal - bringing death
    nonfatal, nonlethal
  2. fateful, fatal - having momentous consequences; of decisive importance; "that fateful meeting of the U.N. declared war on North Korea"- Saturday Rev; "the fatal day of the election finally arrived"
    Antonym: indecisive (indirect, via decisive)
  3. black, calamitous, disastrous, fatal, fateful - (of events) having extremely unfortunate or dire consequences; bringing ruin; "the stock market crashed on Black Friday"; "a calamitous defeat"; "the battle was a disastrous end to a disastrous campaign"; "such doctrines, if true, would be absolutely fatal to my theory"- Charles Darwin; "it is fatal to enter any war without the will to win it"- Douglas MacArthur; "a fateful error"
    Antonym: fortunate (indirect, via unfortunate)
  4. fatal, fateful - controlled or decreed by fate; predetermined; "a fatal series of events"
    Antonyms: evitable, avoidable, avertible, avertable (indirect, via inevitable)