Supposition :: Supposition (n.) The act of supposing, laying down, imagining, or considering as true or existing, what is known not to be true, or what is not proved..
Suppositional :: Supposition (n.) That which is supposed; hypothesis; conjecture; surmise; opinion or belief without sufficient evidence.
Supposititious :: Suppositional (a.) Resting on supposition; hypothetical; conjectural; supposed.
Supposititious :: Supposititious (a.) Fraudulently substituted for something else; not being what is purports to be; not genuine; spurious; counterfeit; as, a supposititious child; a supposititious writing..