To rub something hard in order to clean it, especially using a stiff brush, soap, and water. (Cambridge Dictionary)
Rub (someone or something) hard so as to clean them, typically with a brush and water. (Oxford Dictionaries)
Remove dirt by rubbing hard. (Oxford Dictionaries)
If you scrub something, you rub it hard in order to clean it, using a stiff brush and water. (Collins Dictionary)
Scrub – brush. The Free Dictionary.
Douche and Scrub.