archean
1. [ noun ] (geology) the time prior to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life
Synonyms: archaeozoic_era archean_era archeozoic archeozoic_era archaeozoic
Related terms: era Precambrian
2. [ noun ] (geology) the time from 1.5 billion to 5 billion years ago; earth's crust formed; unicellular organisms are earliest forms of life
Synonyms: Archaeozoic Archeozoic_era Archaeozoic_era archaeozoic_aeon archean_aeon archean_eon archeozoic_eon Archeozoic
Related terms: eon era Precambrian
3. [ adjective ] (geology) used of the earliest known rocks
Synonyms: archaean
Related terms: geology early
Similar spelling:   archaean
  archangel
  arching
  archine
  Arcand
  archness
  arcanum
  arrogant
  Arkansas
  Arkansan
  arachnid