a mountain formed by volcanic material
"The dormant volcano on the island's northern shore has not erupted in centuries but still towers over the landscape as a massive cone of hardened lava and ash."
A vent or fissure on the surface of a planet (usually in a mountainous form) with a magma chamber attached to the mantle of a planet or moon, periodically erupting forth lava and volcanic gases onto the surface.
"Mount St. Helens is an active volcano that recently erupted, spewing molten rock and ash into the sky."
In plain English: A volcano is an opening in Earth's crust that lets hot magma and ash escape to the surface.
"Mount St. Helens erupted like a volcano, sending ash high into the sky."
Usage: A volcano is an opening in Earth's crust that erupts lava and ash from molten rock beneath it. While often described as a mountain shape, its defining feature is this active vent connected to underground magma chambers rather than just being any large hill.
to erupt; to burst forth
"The old volcano erupted violently, sending ash high into the sky and burying the nearby village in debris."
A census-designated place in Amador County, California, United States.
"Residents of Volcano often drive through Amador County to reach nearby towns."
The word "volcano" comes from Italian vulcano, which was named after a small volcanic island in the Tyrrhenian Sea. That name itself derives from Latin Vulcanus, referring to the Roman god of fire and metalworking.