Wiktionary
soap dish
n. a container, which holds a bar of soap.
WordNet
soap dish
n. a bathroom or kitchen fixture for holding a bar of soap
Wikipedia
Soap dish
A soap dish holds a bar of soap when not in use for hand washing or other cleaning, near a washing area such as a bathtub or washbasin. Soap dishes are made from waterproof materials such as plastic, ceramic and metal. Soap dishes may be mounted on the wall. For liquid soap or foam soap a soap dispenser may be used in place of a soap dish.
Soap dishes often feature bumps or ripples which raise the soap, thus allowing the soap to fully dry.