i ‧ on ‧ o ‧ sphere /aɪˈɒnəsfɪə $ aɪˈɑːnəsfɪr/ BrE AmE noun
[ Date: 1900-2000 ; Origin: ion + -sphere (as in atmosphere ) ]
the ionosphere the part of the ↑ atmosphere which is used to help send radio waves around the Earth
i ‧ on ‧ o ‧ sphere /aɪˈɒnəsfɪə $ aɪˈɑːnəsfɪr/ BrE AmE noun
[ Date: 1900-2000 ; Origin: ion + -sphere (as in atmosphere ) ]
the ionosphere the part of the ↑ atmosphere which is used to help send radio waves around the Earth
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012