hydro

Hydro is a combining form derived from the Greek hydor, meaning water. It is used across science and engineering to indicate water-related phenomena, processes, or materials. As a prefix, hydro- signals that water plays a central role in the topic.

In science and engineering, hydro appears in hydrology (the study of water's distribution and movement on Earth), hydraulics (the practical handling of fluids in machines and structures), hydrogeology (groundwater), and hydrography (mapping bodies of water). It also occurs in hydrochemical, hydrometeorological, and related terms that describe water’s chemical, atmospheric, or environmental aspects.

In energy and agriculture, hydroelectric power uses flowing water to generate electricity; pumped-storage and run-of-river schemes are common approaches. Hydroponics describes growing plants in a nutrient solution without soil. Hydrotherapy, or therapeutic use of water, appears in medical and rehabilitative contexts.

In environmental and resource management, hydro-related fields address flood control, irrigation, dam design, and the environmental impacts of water infrastructure, including ecosystem changes and sediment transport. Climate and weather sciences use hydro-related concepts in studying the hydrological cycle and hydrometeorology, which describe how water moves through the atmosphere, land, and oceans.

Because it functions as a prefix rather than a standalone concept, the precise meaning of hydro- depends on the word it accompanies. In general, however, it denotes water or water-related phenomena.