Pronunciation: [mˈə͡ʊst ɐstjˈuːʃəs] (IPA)
Correct spelling for the English word "most astucious" is [mˈə͡ʊst ɐstjˈuːʃəs], [mˈəʊst ɐstjˈuːʃəs], [m_ˈəʊ_s_t ɐ_s_t_j_ˈuː_ʃ_ə_s] (IPA phonetic alphabet).