I. adjective
1.
Synonyms: deadly 1, deathly, lethal, mortal, mortiferous, pestilent, pestilential
2.
bringing on an adverse fate
to accept his word was a fatal mistake
Synonyms: calamitous, cataclysmic, catastrophic, disastrous, fateful, ruinous
Related Word: baneful, pernicious; baleful, malefic, maleficent, malign, sinister; ill-fated, ill-starred, unlucky
Contrasted words: advantageous, beneficial, profitable; auspicious, benign, favorable, propitious
II. noun
Synonyms: fatality 2, casualty, death