Pronunciation: [ɡastˈe͡əɹə͡ʊ] (IPA)
Correct spelling for the English word "gastero" is [ɡastˈe͡əɹə͡ʊ], [ɡastˈeəɹəʊ], [ɡ_a_s_t_ˈeə_ɹ_əʊ] (IPA phonetic alphabet).