Definition of demonstrate

• provide evidence for; stand as proof of; show by ones behavior, attitude, or external attributes; "His high fever attested to his illness"; "The buildings in Rome manifest a high level of architectural sophistication"; "This decision demonstrates his sense of fairness"
• march in protest; take part in a demonstration; "Thousands demonstrated against globalization during the meeting of the most powerful economic nations in Seattle"
• show or demonstrate something to an interested audience; "She shows her dogs frequently"; "We will demo the new software in Washington"