The Collaborative International Dictionary
Castor bean \Cas"tor bean`\ (Bot.) The bean or seed of the castor-oil plant ( Ricinus communis, or Palma Christi.)
Wiktionary
n. The seed of the castor oil plant, ''Ricinus communis''; used in the production of castor oil and of the poison ricin.
WordNet
n. the toxic seed of the castor-oil plant; source of castor oil
Usage examples of "castor bean".
These endless fields of castor bean plants had to be cultivated, but with the great machines that did the work it required but a few dozen men to cultivate an entire county.
The castor bean growers are also going to bring down their prices a lot when this machine kills the market.
White cocoons came from white mulberry leaves, but if the worms were fed the dwarf mulberry, the cocoons were of yellow, and fawn cocoons came when the worms were fed from the castor bean plant.