noun

• A deviation from a rule or from what is regarded as normal; an outlier.
• Something or someone that is strange or unusual.
• (sciences) Any event or measurement that is out of the ordinary regardless of whether it is exceptional or not.
• (astronomy) Any of various angular distances.
• (biology) A defect or malformation.
• (quantum mechanics) A failure of a classical symmetry due to quantum corrections.
• (dated) An irregularity or disproportion.