de·hy·dra·tor noun alsode·hy·drat·er\dēˈhīˌdrād.ə(r), -ātə-\ (-s) : one that dehydrates or operates dehydrating apparatus: as a.: an operator of a still for removing water from lubricating oils b.: an agent (as silica gel) for dehydrating c.: a device or apparatus for dehydrating : dryer