Pronunciation: [ɹˈe͡ɪðnəs] (IPA)
Correct spelling for the English word "ratheness" is [ɹˈe͡ɪðnəs], [ɹˈeɪðnəs], [ɹ_ˈeɪ_ð_n_ə_s] (IPA phonetic alphabet).
Correct spelling for ratheness