Abnormality can be described in many different ways but it is just what’s not normal. The whole concept of abnormality is difficult to define and it comes in many forms that involve different features.
Abnormal psychology is the division of psychology that studies people who are either ‘abnormal’ or ‘atypical’, compared to members of a given society. There is also evidence that some psychological disorders are more common than some previously thought.
There are different definitions of abnormality and they include:

Deviation from social norms:

Within every culture, there are different standards for what is seen as acceptable behaviour or socially acceptable norms. Norms are the expected ways to behave in a particular society according to the majority and for those who do not behave in such a way like everyone else is seen to break these norms. There are defined as abnormal. Social norms differ from culture to culture and what is seen as normal in one culture may be considered completely abnormal to another culture. This is an example of cultural relativism. For example in Southern Europe it is common to stand much closer to strangers, than in the UK. However, there are limitations with this definition and one is that norms can vary over-time. This means that behaviour that was seen as abnormal in one era is no longer defined as abnormal in another. An example of this is drink driving was once seen as acceptable but now it is seen as socially unacceptable. In contrast homosexuality is opposite to this. Up until 1980 homosexuality was considered a psychological disorder by the World Health Organisation (WHO), but today is considered acceptable.

Failure to function adequately:

Failure to function adequately (FFA) refers to the type of abnormality that prevents the individual from carrying out the different behaviours that society would expect from them. Examples of this include holding down a job, conducting successful relationships, and getting out of bed each day etc. If the person cannot cope with these demands of everyday life they are considered abnormal. Rosenhan and Seligman suggest there are seven characteristics that help define FFA and they are: unpredictably and loss of control, suffering, violates moral/social standards, irrationality, maladaptiveness (danger to self), causes of observer discomfort, and vividness and unconventionality (stands out). The strength of this definition is that is provides a practical checklist for the person to use to check their level of abnormality. However, the limitation of it is that FFA may not be linked to abnormality but to other factors such as their economic situation. Also, there are many people who take part in harmful behaviour or is seen as threatening to one self however we do not class them as abnormal. This includes drinking alcohol, adrenaline sports, smoking and skipping classes etc.

This definition of abnormality comes under an individual’s thinking, trait or behaviour. If these of the person are rare or statistically unusual, they are classified as abnormal. However, it needs to be clear how rare a behaviour or trait can be before it is classed as abnormal. For example, one person may say that if an individual who has an IQ score below or above the average level of IQ in society, they are seen as abnormal.
The strength of this definition is that the statistical approach helps to address what is actually meant by normal in a statistical context. It aids us to make cut off points in terms of diagnosis.
The limitations of this definition are that it fails to recognise desirable and undesirable behaviour. For the example of the IQ level being above the normal average, it wouldn’t necessarily be seen as abnormal, but would be regarded as highly desirable. Conversely, obesity is seen as statistically normal but is not associated with desirable or healthy. As this definition implies that the presence of abnormal behaviour in people should be rare of statistically unusual, this is not the case. Any specific abnormal behaviour may well be unusual, but it is not unusual for people to exhibit some form of prolonged abnormal behaviour at some stage in their lives.

Deviation from ideal mental health:

Jahoda (1958) put forward six criteria necessary for ideal mental health and any absences of these characteristics indicted that the individual was abnormal, basically displaying deviation from the ideal mental health. The six criteria by which mental health could be measured are:

Autonomy and independence
Positive view of the self
Accurate perception of reality
Environmental mastery
Positive friendships and relationships
Capability for growth and development

According to this given approach, the more of these six criteria are met, the healthier the individual will be.
However, the limitations of this definition and theory are that it is very difficult for someone to meet the whole criteria and achieve all of the ideal characteristics all the time. For example, a person might not be able to have an ‘environment mastery’ but are happy with their situation. There are very few people who can and this suggests that there are very few people who are psychologically healthy. The absence of this one criteria of ideal mental health does not indicate they are suffering from a mental disorder.