see the geologic time chart in the Reference Supplement
SIMILAR WORDS: ˈperiod
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'eon'
LL < Gr aiōn
, an age, lifetime, eternity < IE base *aiw-
, vitality: see aye1