Short for hydroponic, this system is a plant-growing technique that does not require soil. All the plant\’s nutrients are delivered through nutrients in the water, as opposed to the conventional method of topsoil. The traditional #1excludeGlossary methods require lots of land and space, but a hydroponic system is much more efficient in terms of plant-to-space ratio. The term hydro can also be another synonym for cannabis, but only when the cannabis has been grown in a hydroponic system.
Merriam-Webster Online Dictionary
hydro (noun)British an establishment offering treatment (as for weight loss) - hydropathic health spa
power - hydroelectric
hydroponic, water-grown, soilless cultivation, nutrient solution, aquaculture