C3H5.(CO2H)3

from The Collaborative International Dictionary of English v.0.48

Tricarballylic \Tri*car`bal*lyl"ic\, a. [Pref. tri- + carboxyl +
   allyl + -ic.] (Chem.)
   Of, pertaining to, or designating, a complex tribasic organic
   acid, {C3H5.(CO2H)3} occurring naturally in unripe beet
   roots, and produced artificially from glycerin as a white
   crystalline substance.
   [1913 Webster]