Meaning

noun the supernatural being conceived as the perfect and omnipotent and omniscient originator and ruler of the universe; the object of worship in monotheistic religions

noun any supernatural being worshipped as controlling some part of the world or some aspect of life or who is the personification of a force

noun a man of such superior qualities that he seems like a deity to other people

originSo called from the idea of gods (deities) reigning from on high.

Etymology from Wiktionary, CC BY-SA 3.0