The Collaborative International Dictionary of English v.0.48:

Cinchonidine \Cin*chon"i*dine\, n. [From Cinchona.] (Chem.)
   One of the quinine group of alkaloids, found especially in
   red cinchona bark. It is a white crystalline substance,
   C19H22N2O, with a bitter taste and qualities similar to,
   but weaker than, quinine; -- sometimes called also
   cinchonidia.
   [1913 Webster]