n. The state of a demon. Mede. [ 1913 Webster ]

n. The quality of being demonstrable; demonstrableness. [ 1913 Webster ]

a. [ L. demonstrabilis: cf. OF. demonstrable, F. démontrable. ] 1. Capable of being demonstrated; that can be proved beyond doubt or question. [ 1913 Webster ]

The grand articles of our belief are as demonstrable as geometry. Glanvill. [ 1913 Webster ]

2. Proved; apparent. [ Obs. ] Shak. [ 1913 Webster ]

n. The quality of being demonstrable; demonstrability. [ 1913 Webster ]

adv. In a demonstrable manner; incontrovertibly; clearly. [ 1913 Webster ]

Cases that demonstrably concerned the public cause. Clarendon. [ 1913 Webster ]

n. [ OF. demonstrance. ] Demonstration; proof. [ Obs. ] Holland. [ 1913 Webster ]

v. t. [ L. demonstratus, p. p. of demonstrare to demonstrate; de- + monstrare to show. See Monster. ] 1. To point out; to show; to exhibit; to make evident. Shak. [ 1913 Webster ]

2. To show, or make evident, by reasoning or proof; to prove by deduction; to establish so as to exclude the possibility of doubt or denial. [ 1913 Webster ]

We can not demonstrate these things so as to show that the contrary often involves a contradiction. Tillotson. [ 1913 Webster ]

3. (Anat.) To exhibit and explain (a dissection or other anatomical preparation). [ 1913 Webster ]

adj. having been proved or verified beyond doubt; proved by demonstration. [ WordNet 1.5 ]

n. See Demonstrator. [ 1913 Webster ]

n. [ L. demonstratio: cf. F. démonstration. ] 1. The act of demonstrating; an exhibition; proof; especially, proof beyond the possibility of doubt; indubitable evidence, to the senses or reason. [ 1913 Webster ]

Those intervening ideas which serve to show the agreement of any two others are called “proofs;” and where agreement or disagreement is by this means plainly and clearly perceived, it is called demonstration. Locke. [ 1913 Webster ]

2. An expression, as of the feelings, by outward signs; a manifestation; a show. See also sense 7 for a more specific related meaning. [ 1913 Webster +PJC ]

Did your letters pierce the queen to any demonstration of grief? Shak. [ 1913 Webster ]

Loyal demonstrations toward the prince. Prescott. [ 1913 Webster ]

3. (Anat.) The exhibition and explanation of a dissection or other anatomical preparation. [ 1913 Webster ]

4. (Mil.) a decisive exhibition of force, or a movement indicating an attack. [ 1913 Webster ]

5. (Logic) The act of proving by the syllogistic process, or the proof itself. [ 1913 Webster ]

6. (Math.) 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. [ 1913 Webster ]

7. a public gathering of people to express some sentiment or feelings by explicit means, such as picketing, parading, carrying signs or shouting, usually in favor of or opposed to some action of government or of a business. [ PJC ]

8. the act of showing how a certain device, machine or product operates, or how a procedure is performed; -- usually done for the purpose of inducing prospective customers to buy a product; as, a demonstration of the simple operation of a microwave oven. [ PJC ]

Direct demonstration, or
Positive demonstration, (Logic & Math.), one in which the correct conclusion is the immediate sequence of reasoning from axiomatic or established premises; -- opposed to
Indirect demonstration, or
Negative demonstration (called also reductio ad absurdum), in which the correct conclusion is an inference from the demonstration that any other hypothesis must be incorrect. [ 1913 Webster ]