SUPPOSITITIOUS
conjectural, divinatory, hypothetical, hypothetic, supposed, suppositional, suppositious, supposititious
(adjective) based primarily on surmise rather than adequate evidence; “theories about the extinction of dinosaurs are still highly conjectural”; “the supposed reason for his absence”; “suppositious reconstructions of dead languages”; “hypothetical situation”
Source: WordNet® 3.1
Etymology
Adjective
supposititious (comparative more supposititious, superlative most supposititious)
(obsolete) Spurious; substituted for the genuine, counterfeit; fake.
(obsolete) Imaginary; fictitious, pretended to exist.
Supposed or hypothetical.
Source: Wiktionary
Sup*pos`i*ti"tious, a. Etym: [L. suppositicus. See Supposition.]
1. Fraudulently substituted for something else; not being what is
purports to be; not genuine; spurious; counterfeit; as, a
supposititious child; a supposititious writing. Bacon.
2. Suppositional; hypothetical. [R.] Woodward.
– Sup*pos`i*ti"tious*ly, adv.
– Sup*pos`i*ti"tious*ness, n.
Source: Webster’s Unabridged Dictionary 1913 Edition