Tritheism is the belief that there are three distinct, powerful gods, who form a triad. Generally three gods are envisaged as having separate powers and separate supreme beings or spheres of influence but working together. In this respect tritheism differs from dualism, which typically envisages two opposed Divine powers in conflict with one another.
Most Christian churches do not believe in or teach tritheism, although some nontrinitarian denominations are sometimes characterized as such. The term is often used as an accusation against others, in accusing a group of holding an alternate view of the Christian doctrine of Trinity.
Read more about Tritheism: Monistic Tritheism, Monotheistic Tritheism