Synonyms for Fateful:

adj.

all (adjective)
fatal.
critical (adjective)
crucial.
deadly (adjective)
cataclysmic, ruinous, catastrophic, destructive, fatal, lethal, calamitous, disastrous.
portentous (adjective)
portentous.
prophetical (adjective)
apocalyptical.
ruinous (adjective)
ruinous.
significant (adjective)
critical, portentous, crucial, decisive, momentous, ominous, apocalyptic, direful.

n.

effectively, face to face, situated, undecided, effective, unique, be better/worse off, paradise, circumstantial. ominous. decide, momentous. certain, fated. cataclysmal, catastrophic, destructive, cataclysmic, help, ruinous. baneful, apocalyptic, grave, unlucky, luck, direful, warn, fire and brimstone, apocalyptical, dire, hellfire. fatal (noun)
destructive, ruinous, lethal, deadly.
fateful (noun)
decisive, black, inevitable, prophetical, prophetic, fatal, unfortunate, foreboding, calamitous, disastrous, portentous.
momentous (noun)
crucial, ominous, critical.

Other synonyms:

apocalyptical, hellfire, cataclysmal, cataclysmic, effectively, fire and brimstone, apocalyptic, catastrophic. circumstantial, unique, destructive, dire, fated, situated, baneful, direful. effective, paradise, undecided, momentous, unlucky, face to face. ruinous. foreboding
foreboding, ominous.
Other relevant words:
circumstantial, cataclysmal, dire, apocalyptical, unique, baneful, critical, catastrophic, grave, momentous, cataclysmic, paradise, apocalyptic, help, crucial, decide, luck, undecided, effectively, ruinous, ominous, certain, situated, lethal, deadly, hellfire, warn, direful, unlucky, effective, destructive, fated.

Usage examples for fateful

  1. Only when the house was secure from the destruction which walked in the darkness of that fateful night, could a delivered household gather round the board. – Expositions of Holy Scripture Genesis, Exodus, Leviticus and Numbers by Alexander Maclaren
  2. His manner was wild and excited as he told his short, fateful story; but his eyes, anxious and watchful, never left his listener's face. – The Northern Light by E. Werner