volcano

A volcano is a vent in the earth's crust where molten lava, gases and ash from the interior of the earth are ejected. (noun)

An example of volcano is Mt. St. Helens.

See volcano in Webster's New World College Dictionary

a vent in the earth's crust through which molten rock (lava), rock fragments, gases, ashes, etc. are ejected from the earth's interior: a volcano is active while erupting, dormant during a long period of inactivity, or extinct when all activity has finally ceased
a cone-shaped hill or mountain, wholly or chiefly of volcanic materials, built up around the vent, usually so as to form a crater

See volcano in American Heritage Dictionary 4

(vŏl-kāˈnō)

noun pl. vol·ca·noes or vol·ca·nos

a. An opening in the earth's crust through which molten lava, ash, and gases are ejected.
b. A similar opening on the surface of another planet.
A mountain formed by the materials ejected from a volcano.

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