/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.
[ 1605-15; demonstrator, equiv. to demonstra ( re ) (see DEMONSTRATE) + -tor -TOR ]