<p><strong>Noun</strong></p><ul><li>a person or thing that demonstrates</li><li>a person who takes part in a public demonstration, as by marching or picketing</li><li>a person who explains or teaches by practical demonstrations</li><li>a person who exhibits the use and application of (a product, service, etc.) to a prospective customer</li><li>the product, device, machine, etc., actually used in demonstrations to purchasers or prospective customers</li><li>They sold the demonstrator at half price</li></ul>