Paraphilia was previously known as sexual perversion and sexual deviation. It is the experience of intense sexual arousal to atypical objects, situations, fantasies, behaviors, or individuals.
"The DSM-IV-TR describes paraphilias as "recurrent, intense sexually arousing fantasies, sexual urges or behaviors generally involving nonhuman objects, the suffering or humiliation of oneself or one's partner, or children or other nonconsenting persons that occur over a period of six months" (criterion A), which "cause clinically significant distress or impairment in social, occupational, or other important areas of functioning" (criterion B). (https://en.wikipedia.org/wiki/Paraphilia)
The American Journal of Psychiatry published an article in 1981 describing paraphilia as "recurrent, intense sexually arousing fantasies, sexual urges, or behaviors generally involving: non-human objects,the suffering or humiliation of oneself or one's partner, children, and non-consenting persons.
DSM-IV-TR names eight specific paraphilic disorders (exhibitionism, fetishism, frotteurism, pedophilia, sexual masochism, sexual sadism, voyeurism, and transvestic fetishism, plus a residual category, paraphilia—not otherwise specified). Criterion B differs for exhibitionism, frotteurism, and pedophilia to include acting on these urges, and for sadism, acting on these urges with a nonconsenting person. Some paraphilias may interfere with the capacity for sexual activity with consenting adult partners. In the current version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), a paraphilia is not diagnosable as a psychiatric disorder unless it causes distress to the individual or harm to others." (https://en.wikipedia.org/wiki/Paraphilia)
Sexual perversion depends on the what is meant by normalcy and leads to a wide variety of meanings. If normal sex is whatever minimal erotic activity required to promote conception with an appropriate partner, all else is irrelevant or immoral. If sex is for pleasure to consenting adults then perversion is inflicting pain in the short or long term. If sex is the expression of mutual love, perversions are expressions of hate or being manipulative. If sex is a way of communicating, deceit is a perversion. Masturbation, while not exactly perverse, it is not sexual as talking to yourself is not a whole conversation.