Anomaly

An anomalous phenomenon is an observed phenomenon for which there is no agreeable rational explanation. Because such observations don’t fit into the established framework or consensus reality, they can be the subject of controversy.

Some phenomena aren’t widely accepted as real by mainstream scientists. Ideas about hard-to-reproduce anomalies are often deemed pseudoscientific, partly because science needs phenomena to be reproducible.

Other phenomena are recognized to be real, but can’t be readily explained. For example, many people have observed unidentified flying objects; but their explanations for such objects differ. The Tunguska event was an obvious and undeniable anomaly, but ideas of its cause have ranged from asteroids to cross-dimensional rips.