[kas-ter-oil, kah-ster-] 
| a tall plant, Ricinus communis, of the spurge family, cultivated for its ornamental foliage and having poisonous seeds that are the source of castor oil. |
| cas·tor-oil plant (kās'tər-oil') n. A poisonous, ornamental, tropical African herb or tree (Ricinus communis) having palmately lobed leaves and unisexual flowers and yielding a seed oil of commercial and medicinal value. |
tərˈɔɪl