Definition of demonstrate

• show or demonstrate something to an interested audience; "She shows her dogs frequently"; "We will demo the new software in Washington"
• establish the validity of something, as by an example, explanation or experiment; "The experiment demonstrated the instability of the compound"; "The mathematician showed the validity of the conjecture"
• 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"