Pronunciation: [mˈiːzi͡ən] (IPA)
Correct spelling for the English word "mesion" is [mˈiːzi͡ən], [mˈiːziən], [m_ˈiː_z_iə_n] (IPA phonetic alphabet).
Meson.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
Correct spelling for mesion