Definition of obsidian in English:



mass noun
  • A hard, dark, glasslike volcanic rock formed by the rapid solidification of lava without crystallization.

    • ‘Hard stones such as obsidian and rock crystal were added to the repertoire of the stone-vase maker.’
    • ‘The presence of basalt and obsidian is a sign of volcanic activity and the instability of the earth's crust in this area.’
    • ‘Obsidian looks like coal and while both are black, obsidian is shinier.’
    • ‘Silent as stones like two black pillars carved from obsidian rock.’
    • ‘The earliest mirrors were of obsidian, a black volcanic rock that could be carved and polished.’


Mid 17th century: from Latin obsidianus, error for obsianus, from Obsius, the name (in Pliny) of the discoverer of a similar stone.