n.
Pronunciation: ī - ' ä-n ə - ˌ sfir
Function: noun
Date: 1926
: the part of the earth's atmosphere in which ionization of atmospheric gases affects the propagation of radio waves, which extends from about 30 miles (50 kilometers) to the exosphere, and which is contiguous with the upper portion of the mesosphere and the thermosphere also : a comparable region of charged particles surrounding another celestial body (as Venus)
– ion · o · spher · ic \ ˌ ī - ˌ ä-n ə - ' sfir-ik, - ' sfer- \ adjective
– ion · o · spher · i · cal · ly \ -i-k( ə -)l ē \ adverb