Pronunciation: [wˈɒn sˈa͡ɪddnəst] (IPA)
Correct spelling for the English word "one sidednessed" is [wˈɒn sˈa͡ɪddnəst], [wˈɒn sˈaɪddnəst], [w_ˈɒ_n s_ˈaɪ_d_d_n_ə_s_t] (IPA phonetic alphabet).