Dictionary

castor oil

noun

: a thick oil made from a tropical plant and used in the past as a medicine

Full Definition of CASTOR OIL

: a pale viscous fatty oil from castor beans used especially as a cathartic and as a lubricant and plasticizer

See castor oil defined for English-language learners

See castor oil defined for kids

probably from its former use as a substitute for castoreum in medicine

First Known Use: 1746

CASTOR OIL Defined for Kids

noun cas·tor oil \ˈka-stər-\

: a thick yellowish liquid that comes from the seeds (castor beans) of a tropical herb and is used as a lubricant and as a strong laxative

Medical Dictionary

noun

: a pale viscous fatty oil from castor beans used especially as a cathartic or lubricant

Next Word in the Dictionary: castor–oil plantPrevious Word in the Dictionary: CastoroidesAll Words Near: castor oil

What made you want to look up castor oil? Please tell us where you read or heard it (including the quote, if possible).

Put-downs with flair

How to use a word that (literally) drives some people nuts.

Test your vocab with our fun, fast game

Ailurophobia, and 9 other unusual fears