Definition of: quinine

(kwī′nīn, esp. Brit. kwi·nēn′) noun Chem.
A white, amorphous or slightly crystalline, very bitter alkaloid, C₂₀H₂₄N₂O₂, contained in cinchona barks. Its salts, as the hydrochlorate, sulfate, and others, are largely used in medicine on account of their tonic and antipyretic qualities, especially in malarial affections of all kinds. Also quin·in (kwin′in). [<earlier quina (<Sp. <Quechua kina bark) + -INE²]