WordNet sense 1 (resembling or characteristic of a prophet or prophecy):

sibylline, mantic, sibyllic, vatic, vatical

WordNet sense 2 (foretelling events as if by supernatural intervention):

prophetic, prophetical

WordNet sense 3 (based primarily on surmise rather than adequate evidence):

conjectural, hypothetical, supposed, hypothetic, suppositional, suppositious, supposititious

WordNet sense 4 (concerned primarily with theories or hypotheses rather than practical considerations):

theoretic, theoretical