quinine

1. (pharmacology) An alkaloid with the chemical formula C₂₀H₂₄N₂O₂, originally derived from cinchona bark (from plants of the genus Cinchona), used to treat malaria and as an ingredient of tonic water, which presents as a bitter colourless powder; also, a drug containing quinine or a chemical compound derived from it.Examples: "The alkali of yellow bark may be distinguished from cinchonine by the name of quinine."; "The quinine, being more potent than cinchonine, is generally preferred."; "In spite of quinine, the men sickened day by day. Many of them, fine, strong, active fellows, who had never known what a day's sickness meant, went down before the malarious mist that gathered in the jungles."countableuncountable