A deviation or departure from what is normal, usual, or expected, typically an unwelcome one. Also as a mass noun: deviation, abnormality…

A deviation or divergence. Obsolete.

figurative. Divergence from any course, method, rule, standard, etc.; with a and plural, an instance of this. (The earliest and most frequent sense.)…

Deviation from rule. Obsolete.

figurative. Deviation from what is regular or normal; obliquity, wrongness.

An irregular fact, characteristic, or circumstance; an oddity, an outlier; an anomaly. Also: deviation from what is standard, normal, or expected…

The fact or quality of being anomalous; anomalous character or nature.

A diversion or departure from a recognized course, standard, or norm; an aberration.