Step 1: Expand the term:
FFM stands for the Five Factor Model of personality.
It is also called the Big Five model.
Step 2: Explain the model:
The model says that human personality can be described by five broad traits.
The five traits are openness, conscientiousness, extraversion, agreeableness and neuroticism.
Each trait is a scale. A person falls somewhere between the high and low ends.
Step 3: Link it to personality disorder:
In the Five Factor Model, a personality disorder is seen as an extreme or unhealthy form of the normal traits.
So the model is used to describe and assess such disorders by the trait scores, instead of putting a person in a fixed type.
Final Answer:
FFM means the Five Factor Model, which describes personality by five traits and is used to understand personality disorders.