Webster's Revised Unabridged Dictionary · 1913

(Chemistry) An alkaloid extracted from the bark of several species of cinchona (esp. Cinchona Calisaya) as a bitter white crystalline substance, C20H24N2O2. Hence, by extension (Medicine), any of the salts of this alkaloid, as the acetate, chloride, sulphate, etc., employed as a febrifuge or antiperiodic. Called also quinia, quinina, etc.