adj. & n.
adj. 1 given to or marked by an open expression of feeling, esp. of affection (a very demonstrative person). 2 (usu. foll. by of) logically conclusive; giving proof (the work is demonstrative of their skill). 3 a serving to point out or exhibit. b involving esp. scientific demonstration (demonstrative technique). 4 Gram. (of an adjective or pronoun) indicating the person or thing referred to (e.g. this, that, those).
n. Gram. a demonstrative adjective or pronoun. demonstratively adv. demonstrativeness n.
[ ME f. OF demonstratif -ive f. L demonstrativus (as DEMONSTRATION) ]