a brownish substance containing a mixture of alkaloids formed in the process of extracting quinine from cinchona, formerly used as a substitute for quinine
See quinoidine in American Heritage Dictionary 4
(kwĭ-noiˈdēnˌ, -dĭn)
noun
A brownish-black mixture of alkaloids remaining after extraction of crystalline alkaloids from cinchona bark, used as a quinine substitute.