Correct spelling for the English word "Poristical" is [pɔːɹˈɪstɪkə͡l], [pɔːɹˈɪstɪkəl], [p_ɔː_ɹ_ˈɪ_s_t_ɪ_k_əl] (IPA phonetic alphabet).
Pert. to or depending on a porism.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.