—n. 1. the gaseous envelope surrounding the earth; the air.
2. this medium at a given place.
3. Astron.the gaseous envelope surrounding a heavenly body.
4. Chem.any gaseous envelope or medium.
5. a conventional unit of pressure, the normal pressure of the air at sea level, about 14.7 pounds per square inch (101.3 kilopascals), equal to the pressure exerted by a column of mercury 29.92 in. (760 mm) high. Abbr.: atm.
6. a surrounding or pervading mood, environment, or influence: an atmosphere of impending war; a very tense atmosphere. 7. the dominant mood or emotional tone of a work of art, as of a play or novel: the chilly atmosphere of a ghost story. 8. a distinctive quality, as of a place; character: The old part of town has lots of atmosphere.
—v.t. to give an atmosphere to: The author had cleverly atmosphered the novel for added chills.