Pronunciation: [mˈɑːt͡ʃinəs] (IPA)
Correct spelling for the English word "marchieness" is [mˈɑːt͡ʃinəs], [mˈɑːtʃinəs], [m_ˈɑː_tʃ_i_n_ə_s] (IPA phonetic alphabet).
Correct spelling for marchieness