1a: the dried tuberous root of a Mexican plant (Ipomoea purga synonym Exogonium purga) of the morning-glory family also: a powdered purgative drug prepared from it that contains resinous glycosides
b: the root or derived drug of plants related to the one supplying jalap
2: a plant yielding jalap
First Known Use of jalap
1644, in the meaning defined at sense 1a
History and Etymology for jalap
French & Spanish; French jalap, from Spanish jalapa, from Jalapa, Mexico