The Collaborative International Dictionary of English v.0.48:

Tetracid \Tet*rac"id\, a. [Tetra + acid.] (Chem.)
   Capable of neutralizing four molecules of a monobasic acid;
   having four hydrogen atoms capable of replacement ba acids or
   acid atoms; -- said of certain bases; thus, erythrine,
   C4H6(OH)4, is a tetracid alcohol.
   [1913 Webster]