Oxygen

/ˈɑːksɪdʒən/
B1

Definition, CEFR level B1, pronunciation, examples, and quiz.

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nounA gas in air that people and animals need to breathe.

Extra definitions

nounA colorless gas needed for breathing.

nounThe element with atomic number eight.

nounA gas that supports combustion.

Humans need oxygen to survive.
The tank supplies oxygen.
Fire burns brightly in oxygen.
Synonyms:
None
Antonyms:
None

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.

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.” — 2013 September-October, Katie L. Burke, “In the News”, in American Scientist:
“Look first at any structure to see if there is a carbon with two oxygens attached. Hemiacetals, hemiketals, acetals, and ketals are all alike in that regard.” — 2013, Spencer L. Seager, Michael R. Slabaugh, Chemistry for Today: General, Organic, and Biochemistry, page 479:
CEFR Practice Quiz
Humans need ____ to survive.

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