Paranoid personality disorder
Paranoid personality disorder (PPD) is identified as a personality disorder characterized by an exaggerated sensitivity to rejection, as well as resentfulness, distrust, and an inclination to distort experiences and events. 
Note: The American Psychiatric Association, which publishes the Diagnostic and Statistical Manual of Mental Disorders, forbids the unauthorized reproduction of their diagnostic criteria. A narrative of the DSM-IV-TR criteria follows.
Within the context of this disorder, the neutral and friendly actions of others are often misinterpreted as being hostile or contemptuous, and unfounded suspicions regarding the loyalty of others, particularly the sexual loyalty of partners, is aggressively questioned. Typically, a fixed fantasy that one's rights are not being recognized is a part of the overall belief system. Further, individuals exhibiting a paranoid character can possess an excessive self-assurance and a tendency toward an exaggerated self-reference. This is a compensatory social behavior compelled by the general feeling that one is not being recognized. Pathological jealousy, instinctive aggressive counter-attack, the need to control others, and the gathering of trivial or circumstantial evidence to support jealous beliefs are also features. The term paranoia in this context is not meant to refer to the presence of delusions or psychosis, but implies the presence of ongoing, unbased suspiciousness and distrust of people. 
Current and historical perspectives
Paranoia was initially considered to arise as an adaptive defense against unconscious impulses, a notion derived from the work of Sigmund Freud.  Current interpretation of paranoid behavior has become more complex, although it is still cast in terms of existing constructs, both including defense mechanisms, and the aforementioned fixed fantasies.
Paranoia has also been defined in a less specified manner than the DSM characterization. For instance, Colby refers to paranoia as "the presence of persecutory delusions", an umbrella category that includes distinct somatic, erotic, grandeur, and jealousy delusions. Such delusions may be identified as consistent misinterpretations of events in the paranoid individual's environment. 
The term "paranoia" has been widely exported into common usage, where it does not describe the personality disorder per se, but simply any behavioral tendencies or attitudes indicating excessive anxiety that provokes fear or trepidation.
- American Psychiatric Association. (2000). Diagnostic and Statistical Manual of Mental Disorders. American Psychiatric Press: Washington DC
- Bone, S.; Oldham, J. M (1994). "Paranoia: Historical considerations." In Paranoia: New psychoanalytic perspectives, J. M. Oldman & S. Bone (Eds.). Madison, Connecticut: International Universities Press, Inc.
- Colby, K. M. (1975). Artificial paranoia: A computer simulation of paranoid processes. Toronto: Pergamon Press.