S: (adj) fateful, fatal (having momentous consequences; of decisive importance) "that fateful meeting of the U.N. when...it declared war on North Korea"- Saturday Rev; "the fatal day of the election finally arrived"
S: (adj) 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"
S: (adj) fatal, fateful (controlled or decreed by fate; predetermined) "a fatal series of events"