More fully quina bark: cinchona bark; (also) the bark of various other trees having similar medicinal properties.
Origin
Early 18th century; earliest use found in Phillips's New World of Words. Apparently from Spanish quina cinchona bark, cinchona tree from Quechua kina bark. Compare French (now rare) quina cinchona bark, cinchona tree, and (denoting the bark only) Italian china, Swedish kina.