oxygen
n. uncountablen. a gas that has no color or smell and is necessary for all living things to breathe. It makes up about 21 percent of the air around us.
n. a colorless, odorless, and tasteless gaseous chemical element that is essential for the respiration of most living organisms. It is highly reactive and forms oxides with nearly all other elements.
Humans need oxygen to survive.
The hospital patient was given extra oxygen through a mask to help him breathe more easily during recovery.
Deep-sea divers must carefully monitor their oxygen levels to prevent toxicity, as the partial pressure of gases increases significantly at greater depths.
Etymology tree Proto-Indo-European *h₂eḱ-der.? Ancient Greek ὀξύς (oxús) Proto-Indo-European *ǵenh₁- Proto-Indo-European *-os Proto-Indo-European *ǵénh₁os Proto-Hellenic *génos Ancient Greek γένος (génos) French oxygènebor. English oxygen Borrowed from French oxygène (originally in the form principe oxygène, a variant of principe oxigine ‘acidifying principle’, suggested by Lavoisier), from Ancient Greek ὀξύς (oxús, “sharp”) + γένος (génos, “birth”), referring to oxygen's supposed role in the formation of acids. By surface analysis, oxy- + -gen.
Uncountable in its general sense; can be used as a modifier in compound nouns like 'oxygen tank' or 'oxygen mask'.