half-bath

Short definition from Wiktionary

Noun

1. 1
   A short bath of the feet, limbs, and abdomen that only reaches up to the chest where the upper half of the body is typically kept dry with minimal splashing (especially with water temperature not above 95°F nor below 75°F, and usually prescribed for the sick or unwell as a form of hydrotherapy)
2. 2
   A short bath where the head, especially the hair, is kept dry (especially a shower bath at night before sleep)
3. 3
   Clipping of half bathroom.