suppositious

adjective3

1. •
   Hypothetical, based on supposition; conjectural.
2. •
   Imaginary; fictitious, pretended to exist.
3. •
   Spurious; substituted for the genuine, counterfeit; fake.

   • […] who knowes not how false, how suppositious, the writings and Epistles of the auncient Popes are iustly esteemed? — 1616