Perhaps it had been a hallucination, or it was a false memory. Boggs had even predicted that later Ellis would doubt the incident had even happened—which seemed dispositive toward the dead man's reality…
-- Nick Arvin, The Reconstructionist, 2012
Looks and charm were often dispositive, the more attractive partner sailing on to other waters.
-- Louis Begley, About Schmidt, 1996
Dispositive comes from the word dispose meaning "to put in a particular place."