anomaly
noun [ C or U ] formal uk/əˈnɒm.ə.li/ us/əˈnɑː.mə.li/
异常的人（或事物）；不规则；（同一种类中的）畸形
a person or thing that is different from what is usual, or not in agreement with something else and therefore not satisfactory
Statistical anomalies can make it difficult to compare economic data from one year to the next. 统计上的不规范会使年与年之间的经济数据难以互相比较。
The anomaly of the social security system is that you sometimes have more money without a job. 社会保障制度下的反常现象是，失业有时反而拿钱更多。