Merriam-Webster Collegiate Dictionary - atmosphere

 noun  Etymology: New Latin atmosphaera, from Greek atmos vapor + Latin sphaera sphere  Date: 1677  1.  a. the gaseous envelope of a celestial body (as a planet)  b. the whole mass of air surrounding the earth  2. the air of a locality  3. a surrounding influence or environment an ~ of hostility  4. a unit of pressure equal to the pressure of the air at sea level or approximately 14.7 pounds per square inch (101,325 pascals)  5.  a. the overall aesthetic effect of a work of art  b. an intriguing or singular tone, effect, or appeal an inn with ~  • ~d adjective