The Collaborative International Dictionary
Polytheistical
Polytheistic \Pol`y*the*is"tic\, Polytheistical \Pol`y*the*is"tic*al\, a. Of or pertaining to polytheism; characterized by polytheism; professing or advocating polytheism; as, polytheistic worship; a polytheistic author, or nation. -- Pol`y*the*is"tic*al*ly, adv.
Wiktionary
polytheistical
a. of, or related to polytheism