English▸ noun [mass noun] a hard, dark, glasslike volcanic rock formed by the rapid solidification of lava without crystallization.
▸ adjective made of or resembling obsidian:
the Aztecs placed great value on highly polished obsidian mirrors
a high-gloss obsidian black paint finish.
– ORIGIN early 17th century (as an adjective): from Latin obsidianus, variant of obsianus, from Obsius, the name (in Pliny) of the discoverer of a similar stone.