wild·fire 
/ˈwajəldˌfajɚ/ noun
plural wild·fires /ˈwajəldˌfajɚ/ noun [count] : a fire in a wild area (such as a forest) that is not controlled and that can burn a large area very quickly
▪ The recent wildfires were made worse by the strong winds.
▪ The recent wildfires were made worse by the strong winds.
like wildfire
informal : very quickly
▪ The new fad spread like wildfire.
▪ The new fad spread like wildfire.
