1. To believe especially on uncertain or tentative grounds
   "Scientists speculated that large dinosaurs lived in swamps";
   - theorize, theorise [Brit], conjecture, hypothesize, hypothesise [Brit], hypothecate, suppose
    
2. 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
   "We were speculating whether the President had to resign after the scandal";
   - muse
    
3. Think deeply about a subject or question over a period of time
   "philosophers have speculated on the question of God for thousands of years";
   - chew over, think over, meditate, ponder, excogitate, contemplate, muse, reflect, mull, mull over, ruminate
    
4. Invest at a risk
   "I bought this house not because I want to live in it but to sell it later at a good price, so I am speculating";
   - job

Derived forms: speculating, speculated, speculates

See also: cerebrate

Type of: anticipate, cerebrate, cogitate, commit, expect, invest, place, put, reason, think

Encyclopedia: Speculate