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[ig-nee-uh s] /ˈɪg ni əs/
Geology. produced under conditions involving intense heat, as rocks of volcanic origin or rocks crystallized from molten magma.
of, relating to, or characteristic of fire.
Origin of igneous
1655-65; < Latin igneus, equivalent to ign(is) fire + -eus -eous
Related forms
nonigneous, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for igneous
  • Metamorphic and igneous rocks here show extremely complex structure, which represents a geologic history told in many chapters.
  • igneous rock, unlike sedimentary rock, comes from volcanic activity.
  • The site is strewn with large boulders of dense igneous rock.
  • Tags: detrital zircons, igneous rocks, plate tectonics.
  • Then you run across the odd boulder of igneous rock that must have been below this alluvium.
  • Many igneous rocks, or rocks formed from volcanic eruptions, have a low density.
  • There are three basic types of rock: igneous, sedimentary, and metamorphic.
  • igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies.
  • igneous rocks are those that solidify from a molten or partially molten state.
  • The igneous rock study plays an important role in understanding the tectonic evolution of sedimentary basins.
British Dictionary definitions for igneous


(of rocks) derived by solidification of magma or molten lava emplaced on or below the earth's surface Compare sedimentary, metamorphic (sense 2)
of or relating to fire
Word Origin
C17: from Latin igneus fiery, from ignis fire
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
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Word Origin and History for igneous

1660s, from Latin igneus "of fire, fiery," from ignis "fire," from PIE *egni- "fire" (cf. Sanskrit agnih "fire, sacrificial fire," Old Church Slavonic ogni, Lithuanian ugnis "fire").

Online Etymology Dictionary, © 2010 Douglas Harper
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igneous in Science
  1. Relating to rocks or minerals formed by the cooling and hardening of magma or molten lava. Basalt and granite are examples of igneous rocks.

  2. Relating to the processes, such as volcanism, by which such rocks and minerals form.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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