deviating from the norm
aberrant - unusual
Something ‘aberrant’ is an unwelcome departure from what is considered usual or expected. It often comes in the form of something that does not fit with current moral standards or that shows an untypical lack of self-control. Most commonly used in the noun form ‘aberration'.
I cannot explain his aberrant behaviour recently. It is not at all like him to behave this way.
Alice has never made such a costly mistake before. This was simply an aberration.
Investors are wondering whether the company’s recent poor results are a sign that something is badly wrong, or simply an aberration.