Noah Webster's New International Dictionary of the English Language

1. (n.) The act of demonstrating; an exhibition; proof; especially, proof beyond the possibility of doubt; indubitable evidence, to the senses or reason.

2. (n.) An expression, as of the feelings, by outward signs; a manifestation; a show.

3. (n.) The exhibition and explanation of a dissection or other anatomical preparation.

4. (n.) (Mil.) a decisive exhibition of force, or a movement indicating an attack.

5. (n.) The act of proving by the syllogistic process, or the proof itself.

6. (n.) A course of reasoning showing that a certain result is a necessary consequence of assumed premises; -- these premises being definitions, axioms, and previously established propositions.