1. 
[syn: assumptive, assuming, presumptuous]
2.  accepted as real or true without proof; 
- Example: "the assumed reason for his absence"
- Example: "assumptive beliefs"
The Collaborative International Dictionary of English v.0.48:
Assumptive \As*sump"tive\, a. [L. assumptivus, fr. assumptus,
   fr. assumere.]
   Assumed, or capable of being assumed; characterized by
   assumption; making unwarranted claims. -- As*sump"tive*ly,
   adv.
   [1913 Webster]
   Assumptive arms (Her.), originally, arms which a person had
      a right to assume, in consequence of an exploit; now,
      those assumed without sanction of the Heralds' College.
      --Percy Smith.
      [1913 Webster]
WordNet (r) 3.0 (2006):
assumptive
    adj 1: excessively forward; "an assumptive person"; "on a
           subject like this it would be too assuming for me to
           decide"; "the duchess would not put up with presumptuous
           servants" [syn: assumptive, assuming, presumptuous]
    2: accepted as real or true without proof; "the assumed reason
       for his absence"; "assumptive beliefs"