Behavioral Addiction:
The term addiction is also sometimes applied to compulsions that are not substance-related, such as compulsive shopping, sex addiction/compulsive sex, overeating, problem gambling, exercise/sport and computer addiction. In these kinds of common usages, the term addiction is used to describe a recurring compulsion by an individual to engage in some specific activity, despite harmful consequences, as deemed by the user themselves to their individual health, mental state, or social life. There may be biological and psychological factors contributing to these addictions.
In other words,
If you masturbate despite consequences, or if your masturbation takes precedence over necessary activities, it is an addiction.
Partaking in an activity often, doesn't qualify as an addiction.