Pronunciation: [sˈa͡ɪdli] (IPA)
Correct spelling for the English word "sidely" is [sˈa͡ɪdli], [sˈaɪdli], [s_ˈaɪ_d_l_i] (IPA phonetic alphabet).
There is no standard dictionary definition for the term "sidely." It does not appear to be an established word in the English language.