Deviation from the Social Norms
There are commonly accepted standards of behaviour, some are written laws (no crime etc), and there are some unwritten customs, such as Queueing in the UK.
If someone was to deviate from these norms, it would be an indicator of abnormality. E.g. someone with OCD may wash their hands 50 times per day.
however, there also limitations of defining abnormality this way::
1) eccentric people - abnormal behaviour does not ALWAYS reflect abnormal bevhaviour
2) Context needs to be considered, i.e. crying alot can be seen as abnormal and…