argumentative (adj.)

early 14c., "statements and reasoning in support of a proposition or causing belief in a doubtful matter," from Old French arguement "reasoning, opinion; accusation, charge" (13c.), from Latin argumentum "a logical argument; evidence, ground, support, proof," from arguere "make clear, make known, prove" (see argue). The sense in English passed through "subject of contention" (1590s) to "a quarrel" (by 1911), a sense formerly attached to argumentation.

word-forming element making adjectives from verbs, meaning "pertaining to, tending to; doing, serving to do," in some cases from Old French -if, but usually directly from Latin adjectival suffix -ivus (source also of Italian and Spanish -ivo). In some words borrowed from French at an early date it has been reduced to -y (as in hasty, tardy).