volcano
Americannoun
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a vent in the earth's crust through which lava, steam, ashes, etc., are expelled, either continuously or at irregular intervals.
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a mountain or hill, usually having a cuplike crater at the summit, formed around such a vent from the ash and lava expelled through it.
noun
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an opening in the earth's crust from which molten lava, rock fragments, ashes, dust, and gases are ejected from below the earth's surface
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a mountain formed from volcanic material ejected from a vent in a central crater
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An opening in the Earth's crust from which lava, ash, and hot gases flow or are ejected during an eruption.
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A usually cone-shaped mountain formed by the materials issuing from such an opening. Volcanoes are usually associated with plate boundaries but can also occur within the interior areas of a tectonic plate. Their shape is directly related to the type of magma that flows from them—the more viscous the magma, the steeper the sides of the volcano.
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◆ A volcano composed of gently sloping sheets of basaltic lava from successive volcanic eruptions is called a shield volcano. The lava flows associated with shield volcanos, such as Mauna Loa, on Hawaii, are very fluid.
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◆ A volcano composed of steep, alternating layers of lava and pyroclastic materials, including ash, is called a stratovolcano. Stratovolcanos are associated with relatively viscous lava and with explosive eruptions. They are the most common form of large continental volcanos. Mount Vesuvius, Mount Fuji, and Mount St. Helens are stratovolcanos.
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Also called composite volcano
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See more at hot spot island arc tectonic boundary volcanic arc
Discover More
Volcanoes tend to occur along the edges of tectonic plates.
Eruptions and lava flows associated with them can be very destructive. (See Mount Saint Helens and Mount Vesuvius.)
Other Word Forms
Noun Inflected Forms
Etymology
Origin of volcano
1605–15; < Italian < Latin Volcānus, variant of Vulcānus Vulcan
Explanation
When the earth's crust cracks open and spews hot lava and gases, you've got a volcano on your hands. You better run. The noun volcano comes from the name of the Roman god of fire, Vulcan. The Romans believed Vulcan had a forge in Mt. Etna, a volcano in Italy. The term can be applied to a vent in a planet's surface or crust. Lava, ash, and gas escape through the vent. The term volcano can also apply to a mountain created by such a vent.
Vocabulary lists containing volcano
Physical Geography - Introductory
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Physical Geography - Middle School
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The United States
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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.
See Examples For:
I also avoid making a towering high volcano, instead sticking to small piles or hills, since I like to enjoy my mashed potatoes steaming hot.
From Salon ● Jun. 28, 2026
When Lacaze took the position in 2014, the company had one big thing going for it: its mine, Mount Weld, an eroded ancient volcano in Western Australia with an anomalously high concentration of rare earths.
From The Wall Street Journal ● Jun. 18, 2026
“He’s sitting on a volcano of emotions that he hasn’t dealt with. He does some pretty horrendous things, but I think people softened up to Morrow because they saw that human side.”
From Los Angeles Times ● Jun. 2, 2026
In January 2022, the underwater volcano Hunga Tonga-Hunga Ha'apai in the South Pacific produced one of the most powerful eruptions in modern history.
From Science Daily ● May 10, 2026
But when she came back to the California Institute of Technology in early May and heard what was happening at Mount St. Helens, she knew she had to get up to the volcano.
From "Mountain of Fire" by Rebecca E. F. Barone
First identified by Japanese geologists in 2006, petit-spot volcanoes are small submarine volcanoes that provide evidence for pockets of magma already present near the top of Earth's mantle, an idea originally proposed in the 1960s.
From Science Daily ● Jul. 10, 2026
Seeing the lake, the volcanoes, the vegetation, the flowers, I miss all of that.
From Barron's ● May 21, 2026
"It is known that volcanoes emit methane during eruptions, but until now it was not known that volcanic ash is also capable of partially cleaning up this pollution," he adds.
From Science Daily ● May 10, 2026
It’s worth noting that while there are currently no major volcanoes located along California’s Coast, there are several across the state.
From Los Angeles Times ● Apr. 24, 2026
The welcome feast had made them as sick as volcanoes.
From "Slaughterhouse-Five" by Kurt Vonnegut
One of the most active volcanos on Earth, Kilauea erupts every 2 to 3 years on average.
From Science Magazine ● May 27, 2024
In addition to lava, volcanos eject large amounts of pumice, ashes and gases as a fast-moving flow, known as "pyroclastic flow," and its sediments are a valuable data source on past eruptions.
From Science Daily ● Feb. 22, 2024
It seemed like an eruption might be imminent … but volcanos are fickle.
From Slate ● Dec. 20, 2023
For the past few days, we'd been walking on black beaches formed by lava, driving past enormous craters left by dormant volcanos.
From Salon ● Nov. 17, 2023
The hot cakes rose like little hassocks, and small volcanos formed and erupted on them until they were ready to be turned.
From "East of Eden" by John Steinbeck
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.
