(chiefly British also aeon)
noun (often eons)
an indefinite and very long period of time, often a period exaggerated for humorous or rhetorical effect:he reached the crag eons before I arrived his eyes searched her face for what seemed like eons Astronomy
& Geology a unit of time equal to a billion years.
Geology a major division of geological time, subdivided into eras:the Precambrian eon Philosophy (in Neoplatonism, Platonism, and Gnosticism) a power existing from eternity; an emanation or phase of the supreme deity.