atmosphereat·mos·phere (?t?m?-sfîr?)n.1. The gaseous mass or envelope surrounding a celestial body, especially the one surrounding the earth, and retained by the celestial body’s gravitational field.2. The air or climate in a specific place.3. Abbr. atm Physics A unit of pressure equal to the air pressure at sea level. It equals the amount of pressure that will support a column of mercury 760 millimeters high at 0 degrees Celsius under standard gravity, or 14.7 pounds per square inch (1.01325 × 105 pascals).4. A dominant intellectual or emotional environment or attitude: an atmosphere of distrust among the electorate.5. The dominant tone or mood of a work of art.6. An aesthetic quality or effect, especially a distinctive and pleasing one, associated with a particular place: a restaurant with an Old World atmosphere.[New Latin atmosphaera : Greek atmos, vapor; see wet- in Indo-European roots + Latin sphaera, sphere; see sphere.]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.atmosphere (?ætm?s?f??) n1. (Physical Geography) the gaseous envelope surrounding the earth or any other celestial body. See also troposphere, stratosphere, mesosphere, ionosphere2. the air or climate in a particular place: the atmosphere was thick with smoke. 3. a general pervasive feeling or mood: an atmosphere of elation. 4. (Art Terms) the prevailing tone or mood of a novel, symphony, painting, or other work of art5. a special mood or character associated with a place6. (Chemistry) any local gaseous environment or medium: an inert atmosphere. 7. (Units) a unit of pressure; the pressure that will support a column of mercury 760 mm high at 0°C at sea level. 1 atmosphere is equivalent to 101 325 newtons per square metre or 14.72 pounds per square inch. Abbreviation: at or atm ?atmos?pheric, ?atmos?pherical adj ?atmos?pherically advCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014at?mos?phere (?æt m?s?f??r) n. 1. the gaseous envelope surrounding the earth or a heavenly body; the air. 2. any gaseous envelope or medium. 3. a conventional unit of pressure, the normal pressure of the air at sea level, about 14.7 pounds per square inch, equal to the pressure exerted by a column of mercury 29.92 in. (760 mm) high. Abbr.: atm. 4. a surrounding or pervading mood, environment, or influence: an atmosphere of tension. 5. the dominant mood or tone of a work of art, as of a play or novel. 6. a distinctive quality, as of a place; character. [1630?40; See Also:AIR