Definitions of abnormality

Deviation from social norms:

All societies have social norms, these are not formal laws, but are rules concerning what people expect form the behaviour of others. People who behave in a socially diviant way are considered to be anti-social or undersirable- therefor abnormal by the rest of the group. 

Limitations:

• There is no clear line between what is abnormal deviation and what is harmless, but odd behaviour.
• Cultural relativism.This definition depends on time and culture. E.g. homosexuality used to be considered to be a mental illness. 
• Social deviancy isn't always a bad thing.

Failure to function adequately:

Abnormality…