/ Dictionary / Index A Archaean: Meaning and Definition of Find definitions for: Ar•chae•an Pronunciation: (är-kē'un), [key] — adj. Geol. Archean. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: archaean (Thesaurus) arch archaebacteria Related Content Daily Word Quiz: foliage Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language