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]