We get the English word 'prodigy' from the Latin word prodigium. For the Romans, a prodigium was a sign about the future that came from the gods. Prodigium tended to mean that a calamity was about to happen as the result of the anger of one of the gods. To avert disaster, the Romans made sacrifices or did other acts to propitiate the appropriate god. Particular ominous prodigies required consultation with the Sibylline books or the oracle at Delphi.
Source: William Smith A Dictionary of Greek and Roman Antiquities 1875.