Etymology From Middle English demonstratif, from Middle French démonstratif, from Latin dēmōnstrātīvus. Equivalent to demonstrate + -ive.
1
That serves to demonstrate, show or prove.
demonstrative evidence
an argument necessary and demonstrative[1594], Richard Hooker, edited by J[ohn] S[penser], Of the Lawes of Ecclesiastical Politie, […], London: […] Iohn Windet, […], →OCLC, (please specify the page):
2
Given to open displays of emotion.
demonstrative eloquence1783, Hugh Blair, Lectures on Rhetoric and Belles Lettres:
He had rather a contempt for demonstrative people, arising from his medical insight into the consequences to health of uncontrolled feeling.1865, Elizabeth Cleghorn Gaskell, Wives and Daughters, Chapter III:
3
Grammar, Human sciences, Linguistics, Sciences That specifies the thing or person referred to.