Ar (Noun)

A unit of surface area equal to 100 square meters.

Nouns denoting quantities and units of measure.

A state in south central United States; one of the Confederate states during the American Civil War.

Nouns denoting spatial position.

A colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere.

Nouns denoting substances.

Argon makes up a significant portion of the Earth's atmosphere, about 1%, making it one of the most abundant gases on the planet.
Liquid argon is often used in cooling superconducting materials and high-energy particle accelerators due to its low boiling point.
Neon and argon signs use electrified glass tubes filled with these gases to produce their characteristic glow.
When shield welding with the GMAW or MIG process, a mix of argon and CO2 gases are commonly used as shielding gas.
As argon is non-toxic and doesn't support combustion, it is also used to inflate safety devices and insulated glass windows.