Synonyms of conjectural

2 Syllables
doubtful, suspect, guessing
3 Syllables
supposed, theoretic, figured, stochastic, assumed, accounted, surmised, reputed, surmising, uncertain
4 Syllables
suppositious, tentative, academic, guesstimated, circumstantial, unresolved, ideational, theoretical, putative, refutable, hypothetic
5 Syllables
hypothetical, suppositive, suppository, suppositional, probationary, supposititious