a ‧ nom ‧ a ‧ ly /əˈnɒməli $ əˈnɑː-/ BrE AmE noun ( plural anomalies ) [uncountable and countable] formal
something that is noticeable because it is different from what is usual:
In those days, a woman professor was still an anomaly.
anomaly in
various anomalies in the tax system