Source : Webster's Revised Unabridged Dictionary (1913)

Algonkian \Al*gon"ki*an\, a.
   1. Var. of {Algonquian}.

   2. (Geol.) Pertaining to or designating a period or era
      recognized by the United States Geological Survey and some
      other authorities, between the Arch[ae]an and the
      Paleozoic, from both of which it is generally separated in
      the record by unconformities. Algonkian rocks are both
      sedimentary and igneous. Although fossils are rare, life
      certainly existed in this period. -- n. The Algonkian
      period or era, or system or group of systems.

Source : WordNet®

Algonkian
     adj : of or relating to an Algonquian tribe or its people or
           language [syn: {Algonquian}, {Algonquin}]
     n 1: a member of a North American Indian people in the Ottawa
          river valley of Ontario and Quebec [syn: {Algonkin}]
     2: the Algonquian language spoken by the Algonkian people [syn:
         {Algonkin}]