Hydrogen (noun)

1. A colorless, odorless, flammable gas that is the lightest of all known elements and is present in water, minerals, and all organic compounds.
2. A chemical element with the symbol H and atomic number 1.

Origin:

The word hydrogen comes from the greek words hydro (water) and genes (generator) thus meaning the generator of water.

Examples:

1. Hydrogen is the most abundant element in the universe.
2. Hydrogen fuel cells are a potential source of clean energy.
3. Hydrogen is used as a rocket propellant.
4. Hydrogen can be produced from water by electrolysis.
5. Hydrogen gas is used to inflate weather balloons.