Douglas Harper's Etymology Dictionary
"a form of polytheism characteristic of the Vedic religion, in which one god at a time is considered supreme," 1865, coined in German by Max Müller from Greek kath' hena "one by one" + theism. Müller also coined henotheism (1860), from Greek henos "one," for "faith in a single god" as distinguished from exclusive belief in only one god, in writings on early Hebrew religion.
n. Belief that multiple deities exist, and different deities are supreme among them at different times.
Kathenotheism is a term coined by the philologist Max Müller to mean the worship of one god at a time. It is closely related to henotheism, the worship of one god while not rejecting the existence of other gods. Müller coined the term in reference to the Vedas; where he explained each deity is treated as supreme in turn.