igneous
Americanadjective
-
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.
adjective
-
(of rocks) derived by solidification of magma or molten lava emplaced on or below the earth's surface Compare sedimentary metamorphic
-
of or relating to fire
-
Relating to rocks or minerals formed by the cooling and hardening of magma or molten lava. Basalt and granite are examples of igneous rocks.
-
Relating to the processes, such as volcanism, by which such rocks and minerals form.
Other Word Forms
Etymology
Origin of igneous
First recorded in 1655–65; from Latin igneus “fiery, on fire, burning,” equivalent to igni(s) “fire” + -eus -eous. Ignis is the Latin form of the Proto-Indo-European egni-s, ogni-s, one of the Proto-Indo-European words for “fire,” and it is closely related to Slavic ( Polish ) ogień (inflectional stem ogni- ) and to Sanskrit agni- Agni ( def. ); see fire ( def. )
Explanation
You might remember this one from earth science class. An igneous rock is one that forms through intense, fiery heat — usually in a volcano. It starts out molten (so hot it melts into liquid), then solidifies as it cools. So, it’s rock that has “ignited.” Igneous comes from the Latin ignis, "fire." Granite and basalt are good examples of igneous rock that started out as blazing hot lava and morphed into harder stuff as their temperature dropped. FYI, the other main types of rocks are sedimentary and metamorphic and, technically, you could use igneous to describe other things that are rare or fiery, but it would sound pretty stilted and most people wouldn’t know what you meant.
Vocabulary lists containing igneous
In A Sedimental Mood: Rock and Gem Vocabulary
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Physical Geography - Middle School
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Elements of the Universe: Ign, Igni ("Fire")
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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.
Heavy rare earths are formed over millions of years, as rainfall weathers igneous rocks, breaking them down and leaving elements concentrated near the surface.
From Barron's • Dec. 21, 2025
"Our capability to infer that the maturation stages were somehow influenced by igneous intrusions based on a small sample size is really exciting!"
From Science Daily • May 7, 2024
Now if you were awake in high school science class, you’re thinking, igneous rock: volcanic lava.
From Los Angeles Times • May 3, 2024
Zalasiewicz points out that some rocks originate as liquid, as when lava cools and solidifies into igneous rocks; these rocks form quickly.
From Slate • Apr. 27, 2024
Tonalite, tō′nal-īt, n. an igneous rock having a granitic structure, and composed essentially of plagioclase, biolite, and quartzite.
From Chambers's Twentieth Century Dictionary (part 4 of 4: S-Z and supplements) by Various
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.
