speculate - verb

• to believe especially on uncertain or tentative grounds
• talk over conjecturally, or review in an idle or casual way and with an element of doubt or without sufficient reason to reach a conclusion
• reflect deeply on a subject
• invest at a risk

speculate - thesaurus

conjecture   contemplate   excogitate   hypothecate   hypothesise   hypothesize   job   meditate   mull   muse   ponder   reflect   ruminate   suppose   theorise   theorize