a sign or warning
portent - sign
The formal word ‘portent’ refers to something, such as an omen, that foreshadows or predicts a coming event. While it can be used in both a positive and negative context, it is much more common in the latter form. For that reason, you will most likely encounter this term in relation to a warning or prophetic indication of something bad happening in the future.
I hope the recent downturn in the economy is not a portent of things to come. My business is in dire enough straits as it is.
The manager isn’t helping people by making portentous statements about the future of the company. She should be giving us hard facts, not dire predictions.
The expert spoke portentously about the power and reach of social media platforms, warning the audience that they must do more to protect their privacy.