e|on

e|on «EE uhn, -on», noun.

1. a very long period of time; many thousands of years: »

Eons passed before life existed on the earth.

2. Geology, Astronomy. one billion years: »

Eon [is] geologic shorthand for a period of one billion years (James E. Oberg). “Aeon” is being increasingly used by earth and planetary scientists as a convenient short synonym for “billion years” (Science News).

Also, aeon.

╂[< Latin aeōn < Greek ai lifetime, age]