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1. The outermost region of a planet's atmosphere.
2. The outermost region of the earth's atmosphere, lying above the thermosphere and extending thousands of kilometers into space, from which molecules having sufficient velocity can escape the earth's gravitation.
ex′o·spher′ic (-sfîr′ĭk, -sfĕr′-) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Physical Geography) the outermost layer of the earth's atmosphere. It extends from about 400 km above the earth's surface
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
the highest region of the atmosphere.
ex`o•spher′ic (-ˈsfɛr ɪk, -ˈsfɪər-) adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
The outermost region of the Earth's atmosphere, lying beyond the ionosphere and extending indefinitely into space. The air in the exosphere gets thinner and thinner until the lightest particles, such as hydrogen atoms, begin to escape Earth's gravity.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
the highest portion of the earth’s atmosphere, from which air molecules can escape into space. Cf. ionosphere.See also: Atmosphere
-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.
The outermost layer of the atmosphere of a planet.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited
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|Noun||1.||exosphere - the outermost atmospheric layer|
layer - a relatively thin sheetlike expanse or region lying over or under another
atmosphere - the envelope of gases surrounding any celestial body
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