/ Dictionary / Index C coster: Meaning and Definition of Find definitions for: cos•ter Pronunciation: (kos'tur, kô'stur), [key] — n. costermonger. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Costello Costermansville Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language