lava

(läˈvə, lăvˈə)

noun

1. Molten rock that reaches the earth's surface through a volcano or fissure.
2. The rock formed by the cooling and solidifying of molten rock.

Word History: Lava was appropriately named by people living near Mount Vesuvius. The only active volcano on the European mainland, Vesuvius has erupted frequently since Pompeii and Herculaneum were buried by it in A.D. 79. The Neapolitans who lived in the vicinity took the Italian word lava, meaning “a stream caused suddenly by rain,” and applied it to the streams of molten rock coming down the sides of Vesuvius. The term was then taken into Standard Italian, where it came to mean the rock in both its molten and its solidified states. The Italian word in all its senses was borrowed into English around the middle of the 18th century (1750 being the earliest date of record).