If someone masturbates, they stroke or rub their own genitals in order to get sexual pleasure.
Synonyms: practise self-abuse, touch yourself [informal], play with yourself [informal], practise onanism [formal]
masturbation (mæstəʳbeɪʃən ) uncountable noun The sperm sample is produced by masturbation.
Synonyms: self-abuse, onanism, playing with yourself [slang], autoeroticism