obsidian

[ uh b-sid-ee-uh n ]
/ əbˈsɪd i ən /

noun

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

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Origin of obsidian

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
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Example sentences from the Web for obsidian

British Dictionary definitions for obsidian

obsidian
/ (ɒbˈsɪdɪən) /

noun

a dark volcanic glass formed by very rapid solidification of lavaAlso called: Iceland agate

Word Origin for obsidian

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 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for obsidian

obsidian
[ ŏb-sĭdē-ən ]

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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.