Dew-beater means: An old-fashioned slang term with two related meanings: a person's foot or a crude waterproofed shoe designed to keep feet dry in damp conditions. Both senses evoke the same image - someone stomping. The word is mostly archaic or historical; you will only encounter it in old texts, period drama, or school history rather than current teen conversation. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour.