Stimulation
From Voyeurweb's Wiki
Sexual stimulation is any passive or active activity that leads to sexual arousal or orgasm - not necessarily implying physical stimulation of the genitals.
Physical sexual stimulation usually consists of the touching of parts of the human body, especially erogenous zones.
Mental sexual stimulation consists of any visual images, imagination, reading material, auditory stimulation that causes sexual stimulation and leads to sexual arousal.
Masturbation is considered a type of sexual self-stimulation.
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