To override means to use your authority to cancel or reverse someone else's decision. When a principal overrides a teacher's rule about homework, the principal is using greater power to change what was decided. When Congress overrides a president's veto, they're exercising their constitutional power to pass a law anyway.

The word captures a specific kind of power: actively reversing or ignoring what someone else already decided. A parent might override a babysitter's bedtime, or a judge might override a jury's recommendation. You need the authority to do this: a younger sibling can't override an older sibling's decisions just by disagreeing.

The word also has a technical meaning with machines and computers. When you override automatic controls, you take manual control instead. A pilot might override the autopilot to fly the plane themselves, or a driver might override the cruise control by pressing the brake. The automatic system wanted to do one thing, but the human decided to do something different.

Notice that override doesn't mean “discuss” or “negotiate.” It means decisively replacing one decision with another because you have the power to do so. The word suggests both authority and a certain boldness in using that authority.