Available Definitions:
1) a. - Having the nature of demonstration; tending to demonstrate; making evident; exhibiting clearly or conclusively.
2) a. - Expressing, or apt to express, much; displaying feeling or sentiment; as, her nature was demonstrative.
3) a. - Consisting of eulogy or of invective.
4) n. - A demonstrative pronoun; as, "this" and "that" are demonstratives.