Dormant volcano
A dormant volcano is one which is not currently erupting, but is believed to still be capable of erupting. This contrasts with an extinct volcano, where it is believed that no future eruptions will occur.
In practice, it is often not possible to distinguish between a dormant and an extinct volcano. Volcanoes may remain dormant for thousands of years between eruptions, and several volcanoes thought to be extinct have subsequently re-erupted. Vesuvius was thought to be extinct before its famous eruption of AD 79, which destroyed the towns of Herculaneum and Pompeii, while more recently, the long-dormant Soufriere Hills volcano on the island of Montserrat was thought to be extinct before activity resumed in 1995.