An industrial heat-producing manufacturer in which the prime mover is a steam turbine: Geothermal plants are driven either by vapor produced from hot water or by natural condensation that derives its energy from the hotness found in rock formations of the planet.

Like other related "plant" references, this entry is apparently linked to the action of pressing on a shovel, or some other apparatus, with the "sole of the foot" in order to work the soil for the development of plants.