Definitions for ozone layer
Random House Webster's College Dictionary
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.
ozone layer, ozonosphere(noun)
a layer in the stratosphere (at approximately 20 miles) that contains a concentration of ozone sufficient to block most ultraviolet radiation from the sun
Kernerman English Learner's Dictionary
a layer of gases around the earth that protects it from the sun's heat
A region of the stratosphere, between 15 and 30 kilometres in altitude, containing a relatively high concentration of ozone; it absorbs most solar ultraviolet radiation