/ Dictionary / Index O obsidian: Meaning and Definition of Find definitions for: ob•sid•i•an Pronunciation: (ub-sid'ē-un), [key] — n. a volcanic glass similar in composition to granite, usually dark but transparent in thin pieces, and having a good conchoidal fracture. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: obsidian (Thesaurus) obsessive-compulsive obsidian dating 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