Definition of water whim in English:

water whim

noun

English Regional, Cornwall
Mining
historical
  • A type of hoist in which the descent of a container of water attached to a rope passing over a drum causes the drum to turn and to raise a container at the other end of the rope; also called water whimsey.

Origin

Mid 18th century; earliest use found in William Borlase (1696–1772), antiquary and naturalist. From water + whim.