Basic:
* Hydrate: To combine with water.
* Hydration: The process of adding water.
* Hydrophilic: Attracted to water.
* Hydrophobic: Repelled by water.
* Hydrology: The study of water and its properties.
More complex:
* Hydroelectric: Relating to the generation of electricity from water.
* Hydrogen: A colorless, odorless gas.
* Hydrometer: A device for measuring the specific gravity of liquids.
* Hydraulic: Relating to the use of liquids in machines.
* Hydrocarbon: A compound made up of only hydrogen and carbon atoms.
* Hydrocephalus: A condition where fluid builds up in the brain.
* Hydrangea: A flowering plant.
Scientific terms:
* Hydrolysis: The breakdown of a molecule by the addition of water.
* Hydrophobic interaction: A weak interaction between non-polar molecules.
* Hydration shell: A layer of water molecules surrounding a dissolved ion or molecule.
* Hydrodynamic: Relating to the motion of fluids.
* Hydroponics: The cultivation of plants in water.
Beyond the root "hydr-":
* Hydroxide: A compound containing the OH- ion.
* Aquifer: A body of rock or sediment that holds groundwater.
* Marine: Relating to the sea.
* Aquatic: Living in water.
This list provides a range of examples from the most basic to the more complex, including scientific terms and everyday words. Feel free to ask if you want to learn more about specific words!