WordWeb Online

1. A message expressing an opinion based on incomplete evidence
   - guess, conjecture, surmise, surmisal, speculation, hypothesis
    
2. A hypothesis that is taken for granted
   "any society is built upon certain suppositions";
   - assumption, supposal
    
3. The cognitive process of supposing
   - supposal

Derived forms: suppositions

Type of: conjecture, hypothesis, opinion, possibility, theory, view

Encyclopedia: Supposition