disputatious adj.

late 14c., disputacioun, "formal debate or discussion before an audience or official body regarding the truth of something," from Old French desputasion and directly from Latin disputationem (nominative disputatio), noun of action from past-participle stem of disputare "weigh, examine, discuss, argue, explain" (see dispute (v.)). Earlier was desputeison (c. 1300), from Old French desputaison.

Disputation, as game for teaching logic, was a principal part of the scholastic exercises, and perhaps may still be so in some countries. A master presided, and after a sufficient time decided in favor of one of the disputants, who was then obliged to give his adversary a great thwack with a wooden instrument. [Century Dictionary, 1895]

word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (compare -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."