Source : Webster's Revised Unabridged Dictionary (1913)

Tetrapla \Tet"ra*pla\, n.;

   Note: etymologically pl., but syntactically sing. [NL., fr.
         Gr. tetraplo`os, tetraploy^s, fourfold.]
   A Bible consisting of four different Greek versions arranged
   in four columns by Origen; hence, any version in four
   languages or four columns.