a thick, bitter oil obtained from croton seeds: it is used as a counterirritant and, rarely, as a strong cathartic
See croton oil in American Heritage Dictionary 4
noun
A brownish-yellow, foul-smelling oil obtained from the seeds of a tropical Asian shrub or small tree (Croton tiglium) and formerly used as a drastic purgative and counterirritant. Its use was discontinued because of its toxicity.