Pronunciation: [sɛlˈɪstənˌi͡əm] (IPA)
Correct spelling for the English word "sellisternium" is [sɛlˈɪstənˌi͡əm], [sɛlˈɪstənˌiəm], [s_ɛ_l_ˈɪ_s_t_ə_n_ˌiə_m] (IPA phonetic alphabet).