Source : Webster's Revised Unabridged Dictionary (1913)

Cognation \Cog*na"tion\, n. [L. cognatio.]
   1. Relationship by blood; descent from the same original;
      kindred.

            As by our cognation to the body of the first Adam.
                                                  --Jer. Taylor.

   2. Participation of the same nature. --Sir T. Browne.

            A like temper and cognation.          --Sir K.
                                                  Digby.

   3. (Law) That tie of consanguinity which exists between
      persons descended from the same mother; -- used in
      distinction from {agnation}.

Source : WordNet®

cognation
     n 1: line of descent traced through the maternal side of the
          family [syn: {matrilineage}, {enation}]
     2: related by blood [syn: {consanguinity}, {blood kinship}]
        [ant: {affinity}]