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Definition of the ionosphere noun from the Oxford Advanced Learner's Dictionary

the ionosphere

noun
 
/ði aɪˈɒnəsfɪə(r)/
 
/ði aɪˈɑːnəsfɪr/
[singular]
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  1. a layer of the earth’s atmosphere between about 80 and 1 000 kilometres above the surface of the earth that reflects radio waves around the earth compare stratosphereTopics Spacec2
hide-and-seek
noun
 
 
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