To agitate means to stir something up vigorously or to make someone feel upset and anxious. When you agitate a bottle of salad dressing, you shake it hard to mix the oil and vinegar that have separated. When you agitate water in a bucket, you swirl or churn it rapidly.

The word also describes making people feel disturbed or worried. A confusing announcement might agitate students who don't understand what's happening. Loud, sudden noises can agitate a nervous pet. When someone feels agitated, they're restless and uncomfortable, like they can't sit still or calm down.

In history and politics, an agitator is someone who stirs up public opinion to push for change. Some agitators have fought for important causes like workers' rights or ending child labor. Others have stirred up anger to cause trouble. The word carries a hint of disruption: agitators shake things up, whether that shaking is helpful or not.

You can see how both meanings connect. Just as shaking a jar mixes up its contents, agitating people stirs up their emotions and gets them moving. A washing machine may have an agitator in the center that spins and churns clothes to get them clean.