/ Dictionary / Index C castor sugar: Meaning and Definition of Find definitions for: cas'tor sug"ar Pronunciation: [key] — Chiefly Brit. Chiefly Brit. finely ground or powdered sugar. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. castor-oil plant castrate Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language