ETYM Old Eng. assumpcioun a taking up into heaven, Latin assumptio a taking, from assumere: cf. French assomption. Related to Assume.
1. A hypothesis that is taken for granted; SYN. supposition.
2. The act of taking possession of or power over something; SYN. laying claim.

ETYM Latin praesumptio: cf. French présomption, Old Fren. also presumpcion. Related to Presume.
Audacious (even arrogant) behavior that one has no right to; SYN. presumptuousness, assumption.

ETYM French supposition, Latin suppositio a placing under, a substitution, from supponere, suppositium, to put under, to substitute. The word has the meaning corresponding to suppose. Related to Sub-, and Position.
The cognitive process of supposing; SYN. supposal.

On first consideration