Synonyms for Speculate (same or very similar meaning)
WordNet sense 1 (invest at a risk):
job, jobWordNet sense 2 (to believe especially on uncertain or tentative grounds):
conjecture, hypothesize, suppose, theorize, hypothecate, hypothesise, theoriseWordNet sense 3 (reflect deeply on a subject):
contemplate, meditate, mull, muse, ponder, reflect, ruminate, excogitate, chew over, mull over, think overFrom the ODE community, based on WordNetadd/edit