General terms:
* Dry wash: A common term in the American Southwest, particularly for washes that are dry most of the time.
* Arroyo: A Spanish word for a dry wash, also common in the Southwest.
* Wash: A broad term for a channel that carries water, often dry.
* Gully: A channel carved by erosion, which may be dry.
* Ravine: A deep, narrow valley, often dry.
* Creek bed: A bed that once held a stream, now dry.
More descriptive terms:
* Ephemeral stream bed: A bed that is dry most of the time, only flowing during periods of heavy rain.
* Seasonal stream bed: A bed that carries water during a particular season.
* Intermittent stream bed: A bed that flows intermittently, with periods of flow and periods of dryness.
Specific terms:
* Wadi: (Arabic) A dry riverbed in arid regions.
* Donga: (African) A deep, dry gully, often formed by erosion.
The best word to use depends on the context and the specific characteristics of the stream bed.