So, I'm going to list a few terms here and their correct meanings, so that the next time you read them you'll be able to spot them and go, "Aha! This author so totally didn't do their research here."
psychopath — an individual with a number of distinctive characteristics, including limited emotional capacity, manipulative tendencies, and an absence of guilt or empathy. As in, "The psychiatrist testified that the serial killer was psychopathic." Not to be confused with psychotic. Helpful pop culture example: Dexter.
Psychotic: referring to an individual who experiences a disconnect with reality, in the form of either auditory and/or visual hallucinations, delusions, catatonia, or a thought disorder (in other words, psychosis). As in, "Sally admitted she saw chartreuse flamingoes doing the hula, and the therapist realized that Sally was psychotic." Disorders which may have psychosis as a symptom include schizophrenia, bipolar disorder and depression, and substance abuse can also result in psychosis.
Schizophrenic: describing an individual with schizophrenia — a mental disorder characterized by a combination of symptoms that may include psychosis, personality/behavioural change, and difficulties with social, emotional and cognitive functioning. There are five subtypes of schizophrenia recognized by the DSM (Diagnostic and Statistical Manual of Mental Disorders)-IV: paranoid, catatonic, disorganized, undifferentiated, and residual. Helpful pop culture example: John Nash from A Beautiful Mind.
Dissociative identity disorder: a rare mental illness characterized by two or more identities present within one individual (sometimes termed "alters"). The cause is still not well-understood, although there may be a connection to trauma experienced. This used to be called split, dual, or multiple personality disorder, but the DSM-IV term is dissociative identity disorder. People sometimes confuse this one with schizophrenia, but they are two very different disorders. Helpful pop culture example: Gollum/Smeagol from Lord of the Rings.
Obsessive-compulsive disorder: one type of anxiety disorder that involves obsessions (cognitions) the individual does not want to have, followed by behaviour or mental acts the individual feels compelled to perform to rid themselves of the anxiety brought on by the obsession. I see the term "OCD" thrown around so frequently that you'd think half the population had it, but you can't claim that you have OCD just because you have a particular quirk or obsession. There are specific diagnostic criteria that must be met, just like any other disorder. Not to be confused with obsessive-compulsive personality disorder. Helpful pop culture example: the guidance counselor, Emma, from Glee.
Obsessive-compulsive personality disorder: unlike OCD, this is a personality disorder, not an anxiety disorder. Someone with OCPD has a general preoccupation with perfectionism, order, and control; symptoms include: extreme attention to detail and regulations, rigidity of personal views, dislike of delegating tasks to others, and excessive devotion to work. Unlike OCD, which is ego-dystonic (incompatible with the individual's self-concept, making it unwanted), people with OCPD do not find their symptoms problematic (making it ego-syntonic). Helpful pop culture example: Monica from Friends (admittedly, she's never diagnosed with it, but I suspect she at least has a tendency to OCPD).
Asperger's: a syndrome on the autism spectrum characterized by difficulties with interacting socially, and specific behavioural patterns. This is another term that gets tossed around pretty casually, but once again this is diagnosable; it can't be declared just because someone is quirky, geeky, or anti-social. Helpful pop culture examples: Brennan from Bones and Sheldon from The Big Bang Theory (Sheldon's is unconfirmed, but much of his behaviour is certainly indicative of Asperger's syndrome).
Subconscious: in essence, a word made up by pop psychology. If you're talking about Freudian theory, please do not use this term as it is incorrect. For more info see this Wikipedia article.
Unconscious: Freud's term for the part of the mind that is wholly outside of our own awareness. This, the preconscious, and the conscious make up the mind in Freudian theory.Hope this helps the next time you stumble across a psych term you're not sure about while reading! I know I've only touched on a few here, though, so psychology aficionados: which terms do you find being misused in YA (or other books)?