The term addiction is used in many contexts to describe an obsession, compulsion, or excessive physical dependence. In medical terminology, addiction is a state in which the body relies on a substance for normal functioning and develops physical dependence, as in drug addiction. When the drug or substance on which someone is dependent is suddenly removed, it will cause withdrawal. However, common usage of the term addiction has spread to include psychological dependence. In this context, the term also refers to behaviors that are not generally recognized by the medical community as problems of addiction.
When applied to compulsions that are not substance-related, such as gambling addiction, computer addiction and sexual addiction the term is used to describe a recurring compulsion by an individual to engage in some specific activity, despite harmful consequences to the individual's health, mental state or social life.
A person’s sexual proclivities then would I think be best described as an addiction when there exists an intimacy disorder characterized by compulsive sexual thoughts and acts that like all addictions, have negative impacts on the addict and on family members. Also it would have to be progressive in the sense that over time the “addict” would have to intensify the addictive behavior to achieve the same results.
Examples of sexually addictive behavior include compulsive masturbation or the extensive use of pornography or phone or computer sex services. For others, addiction can involve illegal activities such as exhibitionism, voyeurism, obscene phone calls and child molestation (which we agreed to exclude for the good reason that sex offenders act not for sexual gratification, but rather out of a disturbed need for power, dominance, control or revenge, or a perverted expression of anger). Still to meet the criteria of being an addiction, a person would I think have to engage in persistent and escalating patterns of sexual behavior acted out despite increasing negative consequences to himself/herself or others. In other words, a sex addict will continue to engage in certain sexual behaviors despite facing potential health risks, financial problems, shattered relationships or even arrest.
Most healthy humans have a strong desire for sex and in fact, lack of interest or low interest in sex can indicate a medical problem or psychiatric illness. But we are all unique and some people have a higher sex drive than others. That doesn’t necessarily mean they have an addiction.