supposititious

adjective3

1. •
   Spurious; substituted for the genuine, counterfeit; fake.

   • [...] the said pretended Testament was supposititious, & contriued by such as meant to defraud both the heires female of the said king Henrie the 8. as well as these of his eldest sister [...] — 1600
2. •
   (no longer used) Imaginary; fictitious, pretended to exist.

   • His good sense had pointed out to him the artifices of the monks, and the gross absurdity of their miracles, wonders, and supposititious reliques. — 1796
3. •
   (no longer used) Supposed or hypothetical.

   • “Why this particular problem, Speaker? It obviously has significance other than purely academic.” “Thank you, my boy. You are as quick as I had expected. The problem is not supposititious.” — 1953