1. a person who takes part in a public protest or march to express opposition or support for something
2. a person who shows how something works or is done, especially to teach others
3. a product used to show customers how something works before they buy it

Examples

• Thousands of demonstrators gathered in the city center to protest the new law.
• The police arrested several demonstrators during the march.
• A cooking demonstrator showed us how to make fresh pasta.
• The software demonstrator explained all the program’s features.
• The car dealership let us test drive the demonstrator model.
• She worked as a demonstrator at the electronics store on weekends.