Volcanicity refers to the process or condition of volcanoes, and it's a term typically used by geologists. While there may not be many direct synonyms for volcanicity, there are several related terms that can be used to describe volcanic activity or occurrences. For example, eruption, lava flow, magma, and volcanic activity are all commonly associated with volcanoes. Other synonyms could include volcanic explosions, ash clouds, molten rock, or volcanic vents. Overall, there are many different ways to describe volcanic activity, so while "volcanicity" may not have many exact synonyms, there are plenty of related words that can be used to convey similar meanings.