1. The act of showing or making evident.
2. Conclusive evidence; proof.
3. An illustration or explanation, as of a theory or product, by exemplification or practical application.
4. A manifestation, as of one's feelings.
5. A public display of group opinion, as by a rally or march: peace demonstrations.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.