suppositious
/ˌsʌpəˈzɪʃəs
/adjective
Based on assumption rather than fact: most of the evidence is purely suppositious...
- No wonder Meg left the biz to focus on something a little less suppositious.
Derivatives
suppositiously
suppositiousness
Origin
Early 17th century (in the sense 'supposititious'): partly a contraction of supposititious, reinforced by supposition.