Ether is a chemical that used to be a common anesthetic that you inhaled before undergoing surgery. In most countries, doctors have replaced it with less flammable, safer drugs.
The chemical ether is a colorless liquid that's still used as an anesthetic in some developing countries and as an industrial solvent. The Latin root is aether, which means "the upper pure, bright air." Ether was originally a scientific term for what 19th century physicists called "the fifth element," a substance that was said to fill all space and make up all bodies. In modern times, ether has come to be a literary term that refers to the sky.