anomaly

Definitions of anomaly in various dictionaries:

noun - deviation from the normal or common order or form or rule

noun - a person who is unusual

noun - (astronomy) position of a planet as defined by its angular distance from its perihelion (as observed from the sun)

Deviation or departure from the normal or common order, form, or rule: “NASA’s system for tracking anomalies for flight readiness reviews failed” (Presidential Commission Report on the Challenger Disaster).

One that is peculiar, irregular, abnormal, or difficult to classify: “Both men are anomalies: they have... likable personalities but each has made his reputation as a heavy” (David Pauly).

The angular deviation, as observed from the sun, of a planet from its perihelion.

noun - a deviation from the common rule, type, or form