The Collaborative International Dictionary
cinchonidia
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.
Wiktionary
cinchonidia
n. (dated form of cinchonidine English)