Supervolcano
Volcanologists (who study with volcanoes) and geologists do not say "supervolcanoes" in their scientific work. This is because the word can mean many different geothermal conditions.  Since 2003, however, the term has been used by professionals when showing things to the public.  The term megacaldera is sometimes used for calderas which are quite similar to supervolcanoes, such as the Blake River Megacaldera Complex in the Abitibi greenstone belt of Ontario and Quebec, Canada.