/dem"euhn stray'teuhr/, n.1. a person or thing that demonstrates.2. Also, demonstrant. a person who takes part in a public demonstration, as by marching or picketing.3. a person who explains orteaches by practical demonstrations.4. a person who exhibits the use and application of (a product, service, etc.) to a prospective customer.5. the product, device, machine, etc., actually used in demonstrations to purchasers or prospective customers: They sold the demonstrator at half price.
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