(chemistry) Any of the elements of group 18 of the periodic table, being monatomic and (with very limited exceptions) inert.

A tear gas formed by mixing o-chlorobenzalmalononitrile powder with a dispersal liquid.

Any lachrymatory, non-lethal chemical compound that causes the eyes to sting and water and/or irritates the respiratory system, mostly used for controlling crowds during riots or as self-defense.

To use tear gas.

chloroacetophenone used as tear gas for riot control, although it is normally replaced nowadays with CS gas.

A gas, such as helium or hydrogen, that is used to produce buoyancy for e.g. balloons or airships.

An equal mixture of nitrous oxide and oxygen, used as a mild analgesic and anaesthetic, particularly during childbirth, for dental procedures, and in emergency medicine.

A cylindrical lidded glass vessel for collecting and storing gases from experiments etc.

A sealed chamber in which people are executed with poison gas.

Any gas, such as carbon dioxide or CFCs, that contributes to the greenhouse effect when released into the atmosphere.