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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.


(ˌɛksəʊˈsfɛrɪk) or


(Physical Geography) of or relating to the exosphere
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
Sadly, for someone who achieved so much, Schumacher's 2010-12 was lacklustre by his own exospheric standards.
The Mars Orbiter has five scientific instruments - Lyman Alpha Photometer (LAP), Methane Sensor for Mars (MSM), Mars Exospheric Neutral Composition Analyser (MENCA), Mars Colour Camera (MCC) and Thermal Infrared Imaging Spectrometer (TIS).
Hartnell must have a chance having won the Turnbull as he will definitely stay the trip while Exospheric looks a decent price on the back of his staying-on third in the Caulfield Cup.