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oxygen

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ox⋅y⋅gen

[ok-si-juhn]
–noun Chemistry.
a colorless, odorless, gaseous element constituting about one-fifth of the volume of the atmosphere and present in a combined state in nature. It is the supporter of combustion in air and was the standard of atomic, combining, and molecular weights until 1961, when carbon 12 became the new standard. Symbol: O; atomic weight: 15.9994; atomic number: 8; density: 1.4290 g/l at 0°C and 760 mm pressure.

Origin:
1780–90; < F oxygène, equiv. to oxy- oxy- 1 + -gène -gen


ox⋅y⋅gen⋅ic [ok-si-jen-ik] , ox⋅yg⋅e⋅nous [ok-sij-uh-nuhs] , adjective
ox⋅y⋅gen⋅ic⋅i⋅ty [ok-si-juh-nis-i-tee] , noun
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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ox·y·gen   (ŏk'sĭ-jən)   
n.   Symbol O
A nonmetallic element constituting 21 percent of the atmosphere by volume that occurs as a diatomic gas, O2, and in many compounds such as water and iron ore. It combines with most elements, is essential for plant and animal respiration, and is required for nearly all combustion. Atomic number 8; atomic weight 15.9994; melting point -218.4°C; boiling point -183.0°C; gas density at 0°C 1.429 grams per liter; valence 2. See Table at element.

[French oxygène : Greek oxus, sharp, acid; see ak- in Indo-European roots + French -gène, -gen.]
ox'y·gen'ic (-jěn'ĭk) adj., ox'y·gen'i·cal·ly adv., ox·yg'e·nous (ŏk-sĭj'ə-nəs) adj.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Cultural Dictionary

oxygen

An element, normally a gas, that makes up about one-fifth of the atmosphere of the Earth. Oxygen is usually found as a molecule made up of two atoms. Its symbol is O.

Note: When we breathe in oxygen, it is carried by the hemoglobin in our blood throughout the body, where it is used to generate energy by oxidation. (See respiration.)
Note: Oxygen is a waste product of green plants and photosynthesis.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Word Origin & History

oxygen 
gaseous chemical element, 1790, from Fr. oxygène, coined in 1777 by Fr. chemist Antoine-Laurent Lavoisier (1743-94), from Gk. oxys "sharp, acid" (see acrid) + Fr. -gène "something that produces" (from Gk. -genes "formation, creation"). Intended to mean "acidifying (principle)," from Fr. principe acidifiant. So called because oxygen was considered essential in the formation of acids. The element was isolated by Priestley (1774), who thought it an altered form of common air and called it dephlogisticated air.
Online Etymology Dictionary, © 2001 Douglas Harper
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Medical Dictionary

Main Entry: ox·y·gen
Pronunciation: 'äk-si-j&n
Function: noun
: a colorless tasteless odorless gaseous element that constitutes 21percent of the atmosphere and is found in water, in most rocks and minerals, and in numerous organic compounds, that is capable of combining with all elements except the inert gases, that is active inphysiological processes, and that is involved especially in combustion processes —symbol O; —see ELEMENTtable —ox·y·gen·ic /"äk-si-'jen-ik/ adjective
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Medical Dictionary

oxygen ox·y·gen (ŏk'sĭ-jən)
n.
Symbol O

  1. An element constituting 21 percent of the atmosphere by volume that occurs as a diatomic gas, O2, combines with most elements, is essential for plant and animal respiration, and is required for nearly all combustion. Atomic number 8; atomic weight 15.9994; melting point -218.8°C; boiling point -183.0°C; gas density at 0°C 1.429 grams per liter; valence 2.

  2. A medicinal gas containing not less than 99.0 percent, by volume, of O2.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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