Use 'ungovernable' when describing behavior that's extremely difficult to control or guide. The untamed horse was ungovernable on the track.
Pro Tip 2/3
Extreme Emotion
'Ungovernable' often indicates an overpowering force, like in extreme emotional situations. Her ungovernable joy at the news was infectious.
Pro Tip 3/3
Intensity Level
The word suggests a higher level of intensity than similar words like 'disobedient' or 'naughty'. The team's spirit became ungovernable after several unfair referee calls.