arch[ae]an

2 definitions found

arch[ae]an - Collaborative International Dictionary of English v.0.48 :

  Archaean \Ar*ch[ae]"an\, a. [Gr. 'archai^os ancient, fr. 'archh`
     beginning.]
     Ancient; pertaining to the earliest period in geological
     history.
     [1913 Webster]

  Archaean \Ar*ch[ae]"an\, n. (Geol.)
     The earliest period in geological period, extending up to the
     Lower Silurian. It includes an Azoic age, previous to the
     appearance of life, and an Eozoic age, including the earliest
     forms of life.
     [1913 Webster]
  
     Note: This is equivalent to the formerly accepted term Azoic,
           and to the Eozoic of Dawson.
           [1913 Webster] Archaeobacteria