Oxygen (noun)

1. A chemical element that is a colorless, odorless, tasteless, non-toxic, inert diatomic gas, the chemical symbol for which is O.
2. A gas that is present in the air and necessary for the survival of most living organisms.

Origin:

Early 19th century: from french oxygène, from greek oxus "sharp" + -genes "born of, producing".

Examples:

1. Oxygen is essential for life.
2. The patient was given oxygen.
3. The oxygen tank was empty.
4. The room was filled with oxygen.
5. The rocket carried oxygen for the astronauts.