An omen is a sign or event that people believe predicts something good or bad will happen in the future. When dark clouds gather before a baseball game, some might call them an omen of rain. When a black cat crosses someone's path, superstitious people consider it a bad omen.

Throughout history, people have looked for omens in nature: comets in the sky, unusual animal behavior, or strange weather patterns. Ancient Romans watched how birds flew to interpret omens before making important decisions. Many cultures still consider broken mirrors, finding a four-leaf clover, or seeing a shooting star as omens of various kinds.

An omen differs from a simple prediction because it involves interpreting a sign rather than using logic or science. A weather forecast uses data and patterns; calling those storm clouds an omen adds a mystical or superstitious layer. People today might jokingly call something an omen, like saying “It's a good omen!” when you find a parking spot right in front of the movie theater, even though parking spots don't actually predict the future.