/ Dictionary / Index C castoreum: Meaning and Definition of Find definitions for: cas•tor•e•um Pronunciation: (ka-stôr'ē-um, -stōr'-), [key] — n. castor (def. 1). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. castor bean castor oil Related Content Daily Word Quiz: hale Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language