Portent
Etymology
From Latin portentum, "an omen, sign," from portendere, "to foretell, point out," built from por- (a form of pro-, "forth") and tendere, "to stretch." The idea is of something stretched out ahead as a sign of what is coming. In Roman usage a portentum was a marvel read as a divine warning, and that ominous weight still clings to the word.
noun · /POR-tent/
A sign or warning that something significant, often ominous, is about to happen.
What it names
The word for a foreboding omen — a portent of disaster — usually charged with dread and a sense of large events approaching.
Example
The sudden silence of the birds felt like a portent, though of what, no one could say.
Related idea
Augury is the act or art of reading signs to predict the future; a portent is the alarming sign itself, usually pointing toward something bad.