You searched for: “most supposititious
supposititious (adjective), more supposititious, most supposititious
1. A reference to an idea or belief which hasn't been supported or proven: The supposititious belief of Mr. Smith, the chairman of the committee, that there would be unanimous agreement for the new project turned out to be untrue.
2. A substitution for the real thing; not genuine: She was a more supposititious candidate for congress than her political backers had anticipated.