noun

1. the act, process, or means of making evident or proving
2. an explanation by example, experiment, etc.
3. a practical showing of how something works or is used; specif., such a showing of a product in an effort to sell it
4. a display or outward show a demonstration of grief
5. a public show of feeling or opinion, as by a mass meeting or parade
6. a show of military force or preparedness
7. a logical proof in which a certain conclusion is shown to follow from certain premises

Etymology: ME demonstracion < L demonstratio < demonstrare: see demonstrate