jumping bean

noun

1. the seed of any of certain Mexican plants of the genera Sebastiania and Sapium, of the spurge family: the movements of a moth larva inside the seed cause it to move about or jump.

jumping bean

noun

1. a seed of any of several Mexican euphorbiaceous plants, esp species of Sebastiania, that contains a moth caterpillar whose movements cause it to jerk about

Word History and Origins

Origin of jumping bean¹

An Americanism dating back to 1885–90