/ Dictionary / Index O obsidional coin: Meaning and Definition of Find definitions for: ob•sid'i•o•nal coin' Pronunciation: (ub-sid'ē-u-nl). [key] See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. obsidian dating obsolesc. Related Content Daily Word Quiz: ontiguous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language