demonstrator

Definitions

General English

  • noun a person who marches or who forms part of a crowd protesting against something

Cars & Driving

  • noun a car used by a dealer for test drives and sold at a reduced price after a year or less of use

Commerce

  • noun a person who demonstrates pieces of equipment

Military

  • noun someone who takes part in a demonstration to protest against something

Electronics

  • synonymdemonstration program
http://www.dictionarycentral.com/definition/demonstrator.html