Havoc is widespread destruction, chaos, or disorder. When a tornado tears through a town, it wreaks havoc on buildings, trees, and power lines. When a mischievous puppy gets loose in a house, it might wreak havoc by knocking over plants, scattering toys, and leaving muddy pawprints everywhere.

The phrase “wreak havoc” is most common, meaning to cause serious damage or confusion. A computer virus can wreak havoc on a school's network. A surprise thunderstorm can wreak havoc on an outdoor field day, sending everyone scrambling for cover and ruining carefully planned games.

Havoc suggests more than just a small mess or minor problem. It implies things have gone seriously wrong, creating disorder that takes real effort to fix. If you spill milk, that's a mess. If your little sibling dumps out every puzzle, scatters blocks across the floor, and empties the toy chest while you were supposed to be watching them, that's havoc too.