Omen
Omens are signs encountered fortuitously that are believed to foretell the future. Their interpretation is a form of divination.
The augur and haruspex of ancient Rome were professional readers of omens. The augurs tried to read the future in the flight of birds. The haruspex sought omens in the entrails of sacrificed animals.
Other omens are less subject to putting into a system, and are not voluntarily sought. The superstition that if you break a mirror you will suffer seven years of bad luck is an example of such an omen.
