An extinct volcano is one which is no longer active and hasn't erupted in historical times.
Examples of extinct volcanoes
Mt Warning (Australia)
Chaine des Puys (France)
Some volcanoes lie dormant for thousands of years before erupting again.
Fourpeaked volcano in Alaska erupted in 2004 for the first time in 10,000 years. Geological records show volcanoes in Hawaii may be dormant for one million years before reactivating.