pol·y·the·ism 
(pŏlē-thē-ĭz′əm, pŏl′ē-thēĭz-əm)
(pŏlē-thē-ĭz′əm, pŏl′ē-thēĭz-əm)n.
The worship of or belief in more than one god.
[French polythéisme, from Greek polutheos, polytheistic : polu-, poly- + theos, god; see dhēs- in the Appendix of Indo-European roots.]
poly·the′ist n.
pol′y·the·istic adj.