Suppositious

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

[…] a hen teaches this language with equal ease to the ducklings, she has hatched from suppositious eggs, and educates as her own offspring […]

[…] unfortunately for you, the real Faber and the suppositious Faber, alias Draycott, were much alike in one respect. They gave way to drinking bouts at regular intervals.

At rehearsals the actor tossed an entirely imaginary cloak about his shoulders as though it were heavy brocade, courteously removed a hat made of air, and seriously set out on a suppositious table a non-existent dinner, after sedulously cooking it on a kitchen range that was a chair.

Near-synonyms: assumed, presumed, presumptive, putative, supposed; apparent, likely

Look, Dr. Lanning, let me present you with a suppositious case. Supposing we had a politician who was interested in defeating a reform candidate at any cost and while investigating his private life came across oddities such as I have just mentioned.