/ Dictionary / Index O ozone layer: Meaning and Definition of Find definitions for: o'zone lay"er Pronunciation: (ō-zō'nu-sfēr"). [key] the layer of the upper atmosphere where most atmospheric ozone is concentrated, from about 8 to 30 mi. (12 to 48 km) above the earth, with the maximum ozone concentration occurring at an altitude of about 12 mi. (19 km). Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ozone hole ozone sickness Related Content Daily Word Quiz: blithesome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language