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late 14c., "characterized by logic, based on logic," from Old French démonstratif (14c.), from Latin demonstrativus "pointing out, demonstrating," from past participle stem of demonstrare (see demonstration). Grammatical sense, "pointing out the thing referred to," is mid-15c. Meaning "given to outward expressions of feelings" is from 1819. Demonstrative pronoun is late 16c.