This is the 11554th most frequent Spanish word.
fatídico
Fateful; having a disastrous or prophetic significance.
In this sentence, 'fatídico' is used to emphasize the critical and often tragic significance of the day being described.
El día fatídico en que ocurrió el accidente jamás será olvidado.
The fateful day when the accident happened will never be forgotten.
Here, 'fatídico' highlights the grave and consequential nature of the decision made in the context.
Tomó una decisión fatídica que cambió el curso de los acontecimientos.
He made a fateful decision that changed the course of events.
In this usage, 'fatídico' refers to the foreboding and destined nature of the predictions described.