sign; omen; forewarning
Ancient peoples used to believe that a solar eclipse was a terrible portent that indicated that some terrible event was about to happen.
prodigium (sign, omen, portent, prodigy) (Latin)
On Camping if it pours on your tent it is a omen trekking is going to bad. Portent tells something IMPORTANT is going to happen. (kuch-kuch hota hai)