agitator
ag·i·ta·tor
/ˈæʤəˌteıtɚ/ noun , pl -tors [ count ]
1 usually disapproving : a person who tries to get people angry or upset so that they will support an effort to change a government, company, etc.
The police arrested several antigovernment agitators.
2 : a device for stirring or shaking something in a machine (such as a washing machine)
