adj. relating to any deviation from what is considered typical, usual, or healthy, particularly if the deviation is considered harmful or maladaptive. In statistics, for example, abnormal scores are those that are outside the usual or expected range. The term, however, is most often applied to behavior that differs from a culturally accepted norm, especially when indicative of a mental disorder. —abnormality n. —abnormally adv.
Away from the normal.
Now, we need to understand “Normal”. It’s based on cultural norms, If any person does not follow the norm and values of culture then we called it’s abnormal.