demonstrate in WordNet English dictionary

1. provide evidence for; stand as proof of; show by one's 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"
   attest  certify  manifest  demonstrate  evidence 
   
2. give an exhibition of to an interested audience
   "She shows her dogs frequently"; "We will demo the new software in Washington"
   show  demo  exhibit  present  demonstrate 
   
3. 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"
   prove  demonstrate  establish  show  shew 
   
4. march in protest; take part in a demonstration
   "Thousands demonstrated against globalization during the meeting of the most powerful economic nations in Seattle"
   demonstrate  march