Noun

(wikipedia oxygen)

A chemical element (symbol O) with an atomic number of 8 and relative atomic mass of 15.9994.

Molecular oxygen (O₂), a colorless, odorless gas at room temperature.

* {{quote-magazine, year=2013, month=September-October, author= Katie L. Burke

, magazine=(American Scientist), title= In the News , passage=Oxygen' levels on Earth skyrocketed 2.4 billion years ago, when cyanobacteria evolved photosynthesis: the ability to convert water and carbon dioxide into carbohydrates and waste ' oxygen using solar energy. The evolutionary precursor of photosynthesis is still under debate, and a new study sheds light.}}

(medicine) A mixture of oxygen and other gases, administered to a patient to help him or her to breathe.

(countable) An atom of this element.

Noun

(en noun)

(medicine, oncology, disease) A disease in which the cells of a tissue undergo uncontrolled (and often rapid) proliferation.

* {{quote-book, year=2006, author=(Edwin Black)

, title=Internal Combustion , chapter=1 citation , passage=If successful, Edison and Ford—in 1914—would move society away from the

* {{quote-magazine, date=2013-06-22, volume=407, issue=8841, page=76, magazine=(The Economist)

, title= Snakes and ladders , passage=Risk is everywhere. From tabloid headlines insisting that coffee causes cancer (yesterday, of course, it cured it) to stern government warnings about alcohol and driving, the world is teeming with goblins. For each one there is a frighteningly precise measurement of just how likely it is to jump from the shadows and get you.}}

(figuratively) Something which spreads within something else, damaging the latter.

{{quote-book, year=1999, author=Bruce Clifford Ross-Larson, title=Effective Writing, page=134 citation

, passage=Sierra Leone's post-dictator problems are almost absurd in their breadth. It once exported rice; now it can't feed itself. The life span of the average citizen is 39, the shortest in Africa. Unemployment stands at 87 percent and tuberculosis is spreading out of control. Corruption, brazen and ubiquitous, is a cancer on the economy.}}