a volcanic glass similar in composition to granite, usually dark but transparent in thin pieces, and having a good conchoidal fracture.

1350–1400; < Latin Obsidiānus, printer's error for Obsiānus pertaining to Obsius, the discoverer (according to Pliny) of a similar mineral in Ethiopia; replacing Middle English obsianus < Latin; see -an

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To obsidian
World English Dictionary
obsidian (ɒbˈsɪdɪən)
Also called: Iceland agate a dark volcanic glass formed by very rapid solidification of lava
[C17: from Latin obsidiānus, erroneous transcription of obsiānus (lapis) (stone of) Obsius, the name (in Pliny) of the discoverer of a stone resembling obsidian]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Cite This Source
Word Origin & History

1656, from L. obsidianus, misprint of obsianus (lapis) "(stone) of Obsius," a Roman alleged by Pliny to have found this rock in Ethiopia.
Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
American Heritage
Science Dictionary
obsidian   (ŏb-sĭd'ē-ən)  Pronunciation Key 
A shiny, usually black, volcanic glass. Obsidian forms above ground from lava that is similar in composition to the magma from which granite forms underground, but cools so quickly that minerals do not have a chance to form within it.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source
Example sentences
You're always cogent, but that one was honed to obsidian sharpness.
The new red shirt has a sash with a color called obsidian blue.
Cut marks on the protruding neck bones probably indicate the head had been severed by a sharp obsidian knife.
When obsidian breaks it fractures with a distinct conchoidal fracture.
Copyright © 2014 Dictionary.com, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature