(kol-o -sin' -this) [koXokuvQ'cc, colo- cynth]. Colocynth. Bitter apple. The fruit of Citrullus colocynthis, from which the seeds and rind have been removed. Its properties are due to a bitter glucosid, colocynthin, * CgsH^Oaa, the dose of which is ^Vi gr- (0.003-0.013 Gm.). It is a tonic and as- tringent purgative, and is used mainly as an ingredient of compound cathartic pills.