Wordnet 3.0
ADJECTIVE (1)
1. 
 based primarily on surmise rather than adequate evidence; 
- Example: "theories about the extinction of dinosaurs are still highly conjectural"- Example: "the supposed reason for his absence"- Example: "suppositious reconstructions of dead languages"- Example: "hypothetical situation"[syn: conjectural, divinatory, hypothetical, hypothetic, supposed, suppositional, suppositious, supposititious]
WordNet (r) 3.0 (2006):
suppositious
    adj 1: 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" [syn: conjectural,
           divinatory, hypothetical, hypothetic, supposed,
           suppositional, suppositious, supposititious]