Rubidium (noun)

1. A chemical element with the atomic number 37 and symbol Rb, that is a silvery-white metal.
2. A silvery-white metal that is highly reactive and is found in group 1 of the periodic table.

Origin:

Derived from the latin word 'rubidus' meaning dark red.

Examples:

1. Rubidium is used in atomic clocks, which are the most accurate timekeepers available.
2. Rubidium is often used in photocells and flame photometers, due to its ability to produce light when heated.
3. The properties of rubidium make it ideal for use in specialized applications.
4. Rubidium is not found in its pure form in nature, but rather as a compound in minerals.
5. Rubidium has a low density and is the second most reactive metal, after cesium.