1. (a.) Fraudulently substituted for something else; not being what is purports to be; not genuine; spurious; counterfeit; as, a supposititious child; a supposititious writing.

2. (a.) Suppositional; hypothetical.

Barmecidal Barmecide accounted as affected airy alleged apocryphal apparent apparitional artificial assumed assumptive autistic baseborn bastard bogus brummagem chimeric chimerical colorable colored conjectural conjectured counterfeit counterfeited deceptive deemed delusional delusionary delusive delusory dereistic distorted dreamlike dreamy dressed up dummy embellished embroidered erroneous ersatz factitious fake faked fallacious FALSE falsified fancied fanciful fantastic fatherless feigned fictional fictitious fictive garbled given granted hypothetical illegitimate illusional illusionary illusive illusory imaginary imaginational imagined imitation inferred junky make-believe man-made misbegotten misleading mock natural nonexistent notional ostensible perverted phantasmagoric phantasmal phantom phony pinchbeck postulated postulational premised presumed presumptive pretended pseudo put-on putative quasi queer reputed seeming self-deceptive self-deluding self-styled sham shoddy simulated so-called soi-disant specious spectral spurious supposed suppositional suppositive suppository synthetic taken for granted tin tinsel titivated twisted unactual unauthentic understood unfounded ungenuine unnatural unreal unsubstantial visional visionary warped