Source : Webster's Revised Unabridged Dictionary (1913)

Tetrinic \Te*trin"ic\, a. [See {Tetra-}.] (Chem.)
   Of, pertaining to, or designating, a complex ketonic acid,
   {C5H6O3}, obtained as a white crystalline substance; -- so
   called because once supposed to contain a peculiar radical of
   four carbon atoms. Called also {acetyl-acrylic acid}.