Correct spelling for the English word "bythium" is [bˈa͡ɪθi͡əm], [bˈaɪθiəm], [b_ˈaɪ_θ_iə_m] (IPA phonetic alphabet).
Name given to a substance assumed to be a new element obtained from sulphur.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.