What are the characteristics of abnormal behavior?
"abnormality is defined as maladaptive behavior that results in impairment in adaptive functioning (eg impairs ability to take care of basic needs, to fulfill roles/obligations, to develop/sustain good relationships"
Characteristics depend on what type of abnormal behavior you are observing. For example, if a person seems "sad" to you, is that a sign for depression? The DSM lists characteristics that are symptoms of various disorders. In this case, some symptoms of Major Depressive Disorder can include, "insomnia or hypersomnia nearly every day, significant weight loss when not dieting or weight gain, or feelings of worthlessness or excessive or inappropriate guilt." These are characteristics of abnormal behavior.
Hope this helps? I got this information from my abnormal psychology class!