imˈprobabilize,v.rare. [f. improbable + -ize.] trans. To render improbable. 1820–27Bentham Princ. Judic. Proced.Pref.Wks. 1838–43 II. 5/2 The fear of seeing real improvement obstructed and even improbabilized by the creation of new offices, with enormous salaries attached to them.