[{"Bold_text": "noun", "List Items": ["a person or thing that demonstrates .", "Also a person who takes part in a public demonstration ,as by marching or picketing.", "a person who explains orteaches by practical demonstrations .", "a person who exhibits the use and application of (a product, service, etc.) to a prospective customer.", "the product, device, machine, etc., actually used in demonstrations purchasers or prospective customers:They sold the demonstrator at half price."]}]