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obsidian

American  
[uhb-sid-ee-uhn] / əbˈsɪd i ən /

noun

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

obsidian British  
/ ɒbˈsɪdɪən /

noun

  1. Also called: Iceland agate.  a dark volcanic glass formed by very rapid solidification of lava

"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
obsidian Scientific  
/ ŏb-sĭd′ē-ən /

  1. 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.

Etymology

Origin of obsidian

First recorded in 1350–1400; from 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, from Latin

Explanation

Obsidian is a type of black or dark glass formed from cooling lava. So if you find a shiny, hard, dark piece of glass next time you’re hanging around a volcano, it’s probably a piece of obsidian. The word obsidian essentially means “stone of Obsius.” So who was Obsius? According to an ancient Roman writer, he was the guy who first found this type of stone in Ethiopia. You’ll find obsidian used as a modifier a lot. Think of an obsidian arrowhead, blade or mirror. Sometimes it is used as a fancy way of describing people’s eyes in romance novels as in, “Her eyes were dark and shining, two obsidian orbs.”

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Played by Ebony Obsidian, Lena joins up after her sweetheart is killed in action.

From Los Angeles Times • Dec. 19, 2024

Holly said that particular feature was brought over from games such as Grounded - a co-operative survival adventure from Microsoft studio Obsidian.

From BBC • Apr. 29, 2024

X-ray technology has allowed researchers a glimpse at the reaches of Obsidian Cliff, a mountain of black glass in Yellowstone National Park, and its importance to Indigenous people.

From New York Times • Mar. 22, 2023

It’s a tightly focused labor of love from Obsidian Entertainment director Josh Sawyer, best known for sprawling role-playing epics like “Fallout: New Vegas” and “Pillars of Eternity.”

From Washington Times • Nov. 11, 2022

As I look on, Zero casts a bet of 34.05 notes on the Obsidian Kings.

From "Warcross" by Marie Lu

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.