The phrase "massive wildfires" refers to very large and uncontrollable fires that spread quickly, causing widespread destruction and posing a threat to people, animals, and the environment. Full definition
The state's ongoing drought has helped spark an intense heat wave that's almost literally off the charts, helping to spark massive wildfires and play havoc with the nation's food system. (slate.com)
Australian firefighters battled massive wildfires in bushland around Sydney on Wednesday, but hot weather that could have caused a catastrophic mega-fire did not materialize, allowing authorities to tell some evacuated residents it was safe to return to home. (scientificamerican.com)